I can see a lot of thought-provoking stuff in your post, Feline. I have posted (quite a while ago) about the problems of over-tiredness on the long-distance stuff. I got the bum's rush from a couple of the old hands for this but I think it's certainly something that should be considered. Certainly it is the rider's personal responsibilty not to be unsafe (and I'm hoping for my first SR this season) but I wonder what a court would think of the fact that the minimum speeds for a 600 are the same as for a 200. Certainly the speeds are not colossal but it is (I think) a fair point. We then have the question of whether or not the minimum speed for a 600 is as much to do with an organiser's perfectly-understandable desire to have an event that won't run over into Monday. Slightly OT even 200s are pretty impossible to use public transport to get to for an 8am start, especially since they are nearly all on a Sunday, which is surely a relic of competing or imitating club-runs?
@ millimole: in fairness, there was a lot of media coverage about the driver who caused that bad rail-crash (Hatfield?) but it is true that there is very little, if any coverage of the number of people who are maimed or die at the hands of over-worked doctors, either at work or on their way home. (Preferred your previous avatar, by the way, but current one also good!)
edited for typo and ETA section in bold