I'd be scared of the 200/1.8. Canon doesn't service them anymore, right? Does anybody? I'd hate to have that kind of money in a lens and have the AF break and be stuck with a dud.
I've never really looked at these lenses, but what you post about the two lenses is the feeling I've gotten from reading over at fredmiranda over the years. But Lighter + IS + modern would make me think about the new one.
This thread might be informative. Or not. FM can be hit or miss
Oh, and if you aren't using AF, you might look into a Leica R 180/2. I bet that's a mighty nice lens, and *might* be going for a bit cheaper than they used to since the R is a dead system.