I've been doing it for 15 months now. Went from 190 to 145. I don't miss the foods I thought I would really miss like bread and all the pastas.
I didn't do stage 1, I decided to eat healthy Paleo foods only for a few weeks and when I felt strong I went to stage 2 and stayed on stage 2 for several months. When I shed all the fat/weight I wanted I switched to stage 3.
P90x looks pretty intense so I'm not sure about that aspect. I know there's some intense Paleo athletes out there thou...
http://www.youtube.com/watch?v=m61t3ObnSP0