So I've been using Dvorak for 5 months now, and I'm only up to 80 wpm, which sucks because I used to be 100 with Qwerty. So now that I've got some free time I tried to switch back to Qwerty. I was hoping it would just come back to me...but no. Most of the old neural pathways are erased. After a couple days of trying to relearn Qwerty and only getting back to 20 I now figure the quickest way to get back to 100 will be to stick with Dvorak.
So...advice for people thinking about switching to Dvorak: don't. If you want to type faster just practice with Qwerty. (And learn to touch-type for Christ's sake...although I guess if you can't touch type you aren't thinking about Dvorak.)