Had a chance to compare the Naza M to AMP 2 this weekend and wanted to share the experience.
The comparison was done on two similarly sized custom built quads at ~24" span running the same props, motors, PDU and ESCs. The Naza quad had a Go Pro and Fat Shark FPV 5.8Ghz Transmitter and weighted in at about 3.1 Lbs. The APM Quad (mine) had no additional equipment besides a Sonar and it weighed about 2.75 Lbs.
In general both performed very well with a nod going to the Naza in Loiter, RTL and auto landing due to what appears to be a better GPS. Clearly APM has auto mode and Naza does not.. for the price the APM appears to be a solid value.
As expected both quads were equally stable with no real noticeable difference in stability. The only big difference was NO TUNING on the Naza... it just worked out of the box.
The Naza quad had a noticeable difference in loiter stability and accuracy. Granted my quad my not be tuned perfectly but the Naza held its position more accurately and with less twitching in the wind to do so. The Naza's corrections to the wind seemed to be invisible.. where the APM corrections were noticeable in both pitch and prop noise.
We did a RTL comparison taking off from the same spot and flying about 100 yards away at about 35 feet. The Naza returned to the exact spot of take off. APM got within 10 feet (see below).
Testing the auto landing during RTL..... the Naza descended from 35 feet in what appeared to be about 5 foot increments. It was a very controlled decent. It landed perfectly on home and shutoff. As mentioned the APM quad hit the launch point within 10 feet. Its decent to landing was steadily and constant. When it touched down it then proceeded to skip around on the ground and went another 10 feet from its landing point before shutting down.
The Naza has no autopilot. I finally got all the gremlins out of my APM and flew several successful missions which was very cool.
APM is ~$200 with GPS and Autopilot
Naza is ~$240 + and additional ~$160 for GPS. = $400
I have asked him. He changed the ESC and he thinks that the problem may be gone. That would have been my last guess since they worked quiet well in the video. He already had a Jeti DC16 (1000€) that didn't solve the problem. I still think he had the same RF interference problem (Telemetry, VideoTX, Gopro, opto esc seem unlikely) i had. My naza also did a crazy, fixed, bank angle (in my case tilt left and back). The only thing i could do sometimes to regain control was to switch to the gyro only mode to save it from crashing. My advice for every naza owner is to get an 2€ alubox (connected to GND) and some folding ferrite for the RC and ESC lines. That solved my naza problem.
Thank you very much Randy for looking into this!
I downloaded your 2.9rc1. After flashing, with no powercycle or acc calibration the mp showed -14m. I think that is normal without calibration of any kind and no on/off cycle. After 6-point acc calibration and a short flight i reconnected it to mp and the hight display was correct. I only had a small weather time window for a freeflight. I need to do althold pid tuning but i could see the accz counteracting the hight loss! Great! BTW is there a way to define a separate LPF for accz/baro integration. From what i understand a different lpf is needed than with combinig gyro and acc because the gyro is the fast component there. With baro and acc data combination the acc becomes the fast component.
>Naza has no competition when what you want is a very stable platform with a good failsafe RTL and autolanding. Most people want exactly this and don't need waypoints!
Then the Naza is for them. I don't think anyone is contesting that. It does a good job of doing what it does, and have a very clear market of "my first GPS flight controller". If I had that market, I would be charging as much as I could too.
For the rest of us that desire more features, future development for free, more tuning and headaches, along with open source hardware, the APM is the solution to use currently. I've seen good things from open pilot as well, but I believe they're still lagging on hardware development.
Just to point out here... You do realize that RTL DOES use a waypoint (home) and the only reason you can't set other waypoints is not technical, but solely to get you to pay $700 for their tiered marketing/branded product? There's nothing WRONG with the Naza per se, but.....
I don't know about you, but I get insulted when companies think I'm to stupid to know what they are selling to me.
 removed bad parable 
I don't know how we got to this state, but at every opportunity, I refuse to play these kinds games with these kinds of people. And sorry for the digression, I know this isn't exactly the proper place to get on a soap box. DOH!
Swear I'm done ranting on DJI.
Hopefully they replace at least their multi thousand dollar equipement as well damaged/lost by this bug (Zenmuse, Frame, Motors).........
Actually the boards lit up when people found out the GPS problem and they did not send an email to us about this. You had to HUNT for this at first for about 2-3 weeks. When you first activate a DJI controller it forces an email capture and verification so they knew all of our emails yet they informed no one at all by email, all they did was have a small blurb on their site. Later they added the bigger message. Once again they have everyones emails and if you did not go there you would never know. I assumed with having force captured our email they would let us know about a faulty GPS.
I would say the APM is superb value for money guys, and we have autopilot, and the open platform means it will just get better and better, my hats off to the developers and all the people that put into it, and yes the naza just works but whats the fun in that i like tweaking the settings as im learning all the time... :)
There's a timeconstant which controls how much authority the baro gets over the altitude estimate. So the high speed estimate comes completely from teh accelerometers but as new baro readings arrive, they are used to adjust the position, velocity and underlying accelerometer offsets.
The parameter is INAV_TC_Z. By default it's 7. A high number means rely more on the accelerometers and less on the baro. 7 seems to work pretty well, when it's down at 3 the baro tends to yank around the velocity too much and actually makes the alt hold much worse. If you make it too high then you end up with drift.
I think you'll find 2.9 does a lot better in maintaining your altitude in all situation but especially when you're moving around. While we were working on 2.9 we found that the delay in the barometer (150ms ~ 400ms) really makes it hard to control the altitude well. Also there are aerodynamic effects that mess with the baro. For example if you speed forward and then flatten out the baro will indicate up to 1m change in alt even when i'm 100% sure the copter has not gained or lost altitude. The guess at the moment is that when you flatten out (or lean back a little bit) it creates a little bubble of low pressure around the top of the copter (where the APM is) and the baro sees this as a rise in altitude.
This suggests other sensing possibilities for a barometer. Maybe air and wind speeds can be deduced? With special mounting considerations and surrounding aerodynamics.
I understand the affects of dynamic pressure, but what I observed was different. My baro data follows exactly what I observe in reality; when the quad descends the baro follows. Also last week when I flew in some very gusty conditions I was expecting to see my baro dancing around. Instead I was pleasantly surprised to see alt mode holding it's own within' a foot or so during a hover with the wind was smacking it left and right. Review of tlogs agree... no false readings, and noise levels similar to what I see when it sits in my garage. It was the "nav alt output" that appeared to lag in response to a properly measured descent.
I say the output "appeared to lag", because lowering throttle alt P made it respond faster. If response was sluggish, I would expect decreasing gain to make it worse. I suspect it's not that simple... the apparent lag might have actually been a very low frequency response caused by excessive P gain.
This said, Naza deals well with whatever air pockets it sees, with only very generic settings... versus a complicated layer cake of PIDs worthy of a NASA microgravity UAS project. :P Maybe like Naza, AC should generalize certain things about multirotor performance, and only leave a few settings for end users to "scale" it to their machine.
I have APM 1, 2 and 2.5. I really appreciate the developer’s hard work and the community’s support for the product-it can be very challenging to find and answer to a problem, but it can be found. The features for the money are great! What I really don’t like is the lack of trust I have after every update.
I also have a couple Naza GPS’s and a WKM Single Waypoint V2 and an Atto V3. On these products I really appreciate the performance and confidence they bring in a very short set-up time-far better than APM for what I do.
Specifically to the WK products, support so far has been adequate-certainly not like the large DIY Drones community, but I’ve also had far less issues with the WK products. I have to admit if it weren’t for the APM I wouldn’t know how to tune the WK products so quickly! After one flight they were amazing!
In the end I think each product serves its target market well and if you think ANY product is overpriced and ill-equipped for your mission- then exercise your right not to buy it.