The mask I used before that was also a great mask, the DeVilbiss Aloha. That was the mask that introduced me to the joys of nasal pillows over a full face mask.
Personally, I don't think you could go wrong with either of these masks. For me, the primary advantage of the AirFit P10 is the way the vents work, almost silent, with hardly any feeling of air blowing.
I know what you're talking about, thinking you're not getting enough air. One of the ways I deal with it is to wait after getting into bed a couple of minutes to let my breathing stabilize. That and just trying to relax and not think about breathing. Which is for me a big part of drifting off to sleep anyway.