I don't remember exactly how many 600's i have DNF'd, 4 maybe? I was sick twice, but the other problem I have is that they have been the first ride of the year in hot weather. And the two rides when I was sick were in particularly hot weather, one was really humid too. But the 600 course I am planning on doing is difficult and slow and that might mean I can't sleep. Not looking forward to that. It would be really nice if we have a couple of weeks of hot weather between now and then. And maybe a cold spell for the 600k. I would rather not wait for an easier 600k, the alternatives that I can ride aren't until June.