I began using Dvorak because I heard it could be helpful in reducing RSI symptoms. It took several weeks to become proficient, so I don't recommend learning Dvorak with a big deadline looming. As a programmer, the most frustrating aspect of Dvorak is cut/copy/paste because the X/C/V keys are all over the place. I imagine this would be a problem for hardcore vi users too. The benefit is that my fingers travel less, so typing hurts less.