I used Dvorak for some years, but became frustrated because so many common control key codes are in odd places. then, when I had to alternate between DVORAK and QWERTY layouts, I slowed right down. Now I'm back to using a single keyboard, I use the Colemak
layout, and am very happy with it. It's a l'ot easier to learn if you already touch-type in Qwerty, and the Z,X,C,V keys are in the same place
As far as I can tell its just as fast as Dvorak for lengthy text input, and even more comfortable because there is less work for the little fingers!