MChase, My butt definitely hurts more when I do more high pressure pieces. No matter what, more than an hour in my boat is somewhat uncomfortable. It always has been but I have almost no back pain at all. I'm asuming that every rower's back is a little painful or strained after every training session. It seems that when doing high pressure work I lift my butt off of my seat a little, or at least lighten the contact, and then drop it back down at the release. I thought that was the reason for more butt discomfort. Changing seats and seat pads around has helped a lot and it seems that my butt pain is getting better. I have always tried to get as low in my boat as possible but I may try adding that 1cm recommended by platypus. Tomorrow I'm trying the larger of the two seats I got from Dreher (I had to grind quite a bit off the sides of the seat to fit it to my boat) and my sorbothane pad. I'll take the Skwoosh pad along incase I need it too. The holes in the large seat are a lot bigger than the ones in the smaller seat.
I usually win if none of the guys who are faster than I am show up and if I don't go off course.