Finally I've managed to have some time and do a little flight to test the Arducopter v2.1 firmware.
Here is my quad and some specs I hope you find them usefull somehow :
Weight (with camera on board) : 1700gr
Weight (without camera) : 1500gr
Battery : Turnigy 5000mAh 3S / 30-40C
Motors : 4 x EMAX GT 2812-11 930KV (about $15 each from plus2city - behaving very well so far)
ESCs : 4 x AE 30Amp (about $12 from hobbywing, behaving surprisinglly well so far)
APM 2560 + oilpan + Ardcuopter 2.1 firmware
12x4.5 propellers (not the best ones, this are a little soft, I'm waiting for some stiffer ones)
I got about 10m flight time with the camera
PID Rate Roll (and Pitch) adjusted to 0.075 (default was 0.145 but I got to much oscillations. The in flight PID adjustment using ch6 it's no doubt a super add on. I had never touched the PIDs before, but now I really needed since the quad was oscillating too much, especially on descents).
PID Stabilize Roll (and Pitch) adjusted to 4.550 (default was 4.5)
This 2 Videos, are from the same flight.
First one, videocamera from the ground (most of the time you don't see the quad, since I had no cameraman :) , but if you look closely towards the end, you will have a great chance to watch my belly eheheh)
Second video from camera on board. I left the time stamp so you can check the battery duration. Conditions were almost perfect. No wind at all, about 13ºC.