P90X X Stretch is awesome. I did P90X four times in a row and never had any injuries or extreme soreness. Even though I'm now doing X-Train, I still follow the P90X routine with yoga on Thursday and X Stretch on Sunday. I try to sneak in another short yoga workout on Saturday morning as well.
I would also recommend using a recovery drink. It helps. I use Beachbody's Results & Recovery drink.
I also try to work in a recovery week as well. I follow the P90X recovery week schedule.