Honestly, the only complaint anyone has about the P10 is the headgear. I like it more than the FX headgear, and it is minimal and light, but the complaint about adjustment is a constant whine here, and probably rightfully so. No one ever complains about it being too loose, so maybe it should be produced slightly bigger.
It is actually pretty clever, but the range of adjustment might not be optimal. I just give it a good stretch just before putting it on. If it tightens up later, I am probably already asleep.
My sincere hope is that the P10 or whatever succeeds it addresses this common complaint. They could include in the kit a second, larger headstrap and instructions without a significant cost increase, or they could offer the P10L. (hint hint)
I wear a 7-5/8 to 7-3/4 inch hat and a 2X or XXL helmet. I can barely fasten the straps on an adjustable ball cap. I was afraid the P10 wouldn't fit me comfortably, but it does, with the straps split one on the back of my head and one on the top (thanks, AshSF!). The strap is incredibly stretchy. It leaves no marks on my cheeks, nor does it put pressure on my nose.
I titrated with the Swift FX, which IIRC, is about twice the weight of the P10 (neither are that heavy). It has a very forceful exhaust jet that hit my arm and could certainly reach across the bed to my wife. Didn't bother me because I sleep under a ceiling fan, but that forceful exhaust is a bit louder. The P10's exhaust is well diffused. I can feel just a very gentle breeze on my arm hairs.
I am VERY happy the P10 worked out for me.