Yes: I switched about 14 years ago. It took me about three (frustrating) weeks until my Dvorak speed caught up to my querty speed---it isn't noticeably faster for me---but my wrist and hand pain completely disappeared after about a week.

Furthermore, if you actually switch back even for a few minutes once a week or so, your Qwerty typing won't atrophy much at all.

However, I wouldn't bother switching unless you're pretty sure that you're going to be spending several hours a day typing, and mostly on the same small number of computers. Reconfiguring any modern computer back and forth between Qwerty and Dvorak is easy, but it's completely maddening for anyone with whom you share a computer.