I switched to Dvorak about 15 years ago. I agree with others here: I switched from being a Qwerty typist with poor form, to a "correct" Dvorak typist. In the end I'm a pretty speedy typist (~130 wpm), but I can still Qwerty well enough that it isn't painful.
However, I think the speed-up can mostly be attributed to forcing me to have a clean slate and learn to type correctly, rather than any intrinsic advantage of Dvorak.
On Qwerty I typed the style I'd evolved since elementary school, and on Dvorak I touch-type like I'm meant to.
Same here -- I jumped from about 70 on Qwerty to about 130 on Dvorak. I think it's almost entirely due to the fact that I now type "correctly", rather than anything great about Dvorak. (I don't really recommend switching to other people, but I don't have the motivation to move back.)
Does everyone mean the same thing by "wpm"? I almost always score over "125 wpm" on Typeracer.com, and there are plenty of people there who score higher than that. So I suspect there is some inconsistency in the counting between that site and the article. (I don't even consider myself especially fast.)
(I know the Elm people don't like jokes about the email client. Tough; they should have picked a name that wasn't already used.)