Seems like everyone has anecdotal issues with the Air2, and in over 30 years of diving one, I have never had a problem.
It is a proven piece of equipment, which, as with all other equipment, used and maintained properly, continues to function as designed.
I'm not saying it's a bad piece of kit, I've only dived the second version of the air2 and in my opinion it just doesn't breathe optimal compared to a good second stage.
Ofcourse it works, but you can't get the breathing as light as let's say a properly tuned g250 or s600 or whatever balanced second stage with a big diaphragm and high quality poppet that can be tuned under 1.0
Another issue I have with it, is that you need a long inflator. I usually run them very short so they dont flop around and interfere with d-rings.