If you do switch you have to go cold turkey. Otherwise your brain will be going two directions at once and you'll never get good at Dvorak.

Resign yourself to a month or two of being slow. It wasn't until 6 weeks after switching that I was back up to my previous speed.

I can still type QWERTY when need be, but I'm slower at it than before. Maybe half as fast. But when I do use it it feels silly, my fingers flailing all over the keyboard like a spider ummm ... doing a tarantella.