Completed my very first quad 'flight' ever today with my DJI Flamewheel 450. I'm using the APM 2.5 with APM Copter 2.9.1b. I say 'flight' because all I did was a bit of hovering to check out my vibration dampening efforts, although there was a constant light wind (<5 kts) that I had to compensate for.
I'm using a Spektrum DX6i xmtr and receiver, 10x4.5 GemFan props that were recommended elsewhere in these forums, plus the standard ESC's and motors that come with the 450 frame. The battery is a Turnigy 2650 mah/35-70C 3S. All motors and props were balanced. I used the 4-run method for the motor balancing and a Du-Bro balancer for the props.
First impression was it was much quieter than I expected. From some of the videos I'd seen I was expecting a swarm of angry hornets, but it turned out to be more of a gentle electric hum.
The receiver and GPS mounting were temporary as I hadn't received my taller set of standoffs to make the second level of my mounting platform.
I originally was going to make the APM platform out of acrylic but had trouble with the corners breaking off as I tried to drill it, so I just made it out of 1/8" balsa plywood instead.
I mounted the standoffs on the top flamewheel board at the center of the 'X' made by drawing a line between the existing screw holes for the arms. It turns out that a 2.25" square board fits nicely between these for an o-ring mounting. I used 017 sized silicone o-rings sandwiched between two washers. I also put dampening gel under the corners of the APM as you can see in the following picture:
The gel is called PU Adhesive Gel and is made by a company called Align. I got it at my local helicopter hobby store. Its used for mounting gyros, etc. The gel has some stickiness but not enough to hold down the APM, so I CA'd the gel squares to the mounting board, but just held down the APM to the gel with a velcro strap wrapped around the whole assembly.
The following are my vibration results. It seems ok for my first try. Maybe when I take the receiver off the APM's back (held with velcro at the moment) it will improve a bit.