Thanks all. Depending on how my month goes, I'm contemplating doing a 600 in mid June. We'll see. Easier course and if I can get some solid riding in (heck I did a 140 this weekend after all - good training!) it may work. I know my hip *can* do a 600 (it didn't hurt at all during the 400), but I just need to be smarter about things than I used to be. Like the first time I did this ride.