Maybe I'm wierd, but I think slow greens are MUCH harder to putt. Because you have to hit the ball harder, it is easier to make a poor stroke. Also, slow greens tend to be more inconsistant.
I'm not so sure that the big boys would disagree. Whenever they get stuck with slow greens, they complain. As long as they're not Shinnecock silly, I think they prefer fast (11-12) greens. If they're stuck with 9's, my guess is scores would actually go up ... and they'd bitch.