I switched to both Vim and Dvorak cold turkey at the beginning of this year. (I figured as long as I can't type, might as well be unable to edit things too.) I am not sure if not having prior knowledge of QWERTY Vim makes any difference, but I have seen no downside to using Dvorak. The most common complaint I see--the hjkl thing--isn't even an clear-cut disadvantage. Now they are on two different hands and I think it makes movement faster. Vim commands are all mnemonic, so unless you Vim has penetrated so deep into the subcortex that it's all muscle memory, learning shouldn't be much of a problem.

Definitely gratifying to hear this guy's experience, BTW. I got religion when it comes to Vim. If you spend 8-10 hours a day editing text, it makes sense to put some thought into how you are doing it. Small efficiency gains add up.