I have been using the p10 for nearly three years and just changed to the p30i, which my sleep clinic now gives out as a free replacement (East Grinstead NHS, UK). Tried it for a few days now. Pros - the strap doesn't seem to require the same amount of tension or seem to slip around so much behind my...

I had sore nostrils when I was using the wrong size pillow, but it sounds like you have tried all the other sizes. I used vaseline to help heal the soreness. If you want to stick with pillows you might consider the resmed p30i, the strap doesn't seem to require the same amount of tension and I have ...