Yep, I'm about 110 wpm without adjustment last time I clocked on a regular keyboard, but I can't maintain this for long periods of time. I suspect that ergonomic keyboards allow you to maintain high speeds, not necessarily to reach them. I don't personally don't find myself slower on, for instance, my old natural elite.

My only written reference is the material by "ergonomic experts" included with my Kinesis Advantage -- a bit on the unreliable side. Would love to know if you and Google can turn up anything else.