Top Dvorak Typist: 140 wpm

I use QWERTY and I can definitely maintain 140WPM easily when typing something from memory or when participating in realtime chat. In short bursts, ~230WPM isn't difficult. A look at sites like TypeRacer shows that there are indeed many typists who can achieve 150-160WPM, and some occasionally exceed 200.

That said, I think typing speed is highly dependent upon the keyboard, and layout is only one of many other factors. From personal experience I have a feeling most keyboards out there are extremely suboptimal, with too much key travel and heavy actuation force. I've not be able to go above 130WPM on any laptop keyboard, for example, and even trying to achieve 100 feels extremely tiring. On the other hand, my desktop keyboard happens to have extremely light keys and shallow travel with a good bouncy "cushion" at the end, and I can type for many hours at much higher speeds without feeling tired.

Steno's biggest advantage comes from having very long words produced with a single chord, but the average word length is not so high, and most faster typists I know, as do I, already somewhat "chord" keys for common sequences (otherwise transposition errors wouldn't appear at all --- "hte" instead of "the" being one example, as those with experience will tend to hit both keys almost simultaneously for that.)