korell: As for typing speed, layout isn't so much of a factor. I believe that there have been studies on keyboard layouts and for a skilled typist even randomized and alphabetical layouts allow similar typing speeds after the initial stage of getting used to the new layout.
etb: Citation needed.
Well, this is a starting point anyway:
"Several alternatives to QWERTY have been developed over the years, claimed by their designers and users to be more efficient, intuitive and ergonomic. Nevertheless, none has seen widespread adoption, partly due to the sheer dominance of available keyboards and training. Although some studies have suggested that some of these may allow for faster typing speeds, many other studies have failed to do so, and many of the studies claiming improved typing speeds were severely methodologically flawed or deliberately biased, such as the studies administered by Dvorak himself before and after World War II. Economists Stan Liebowitz and Stephen E Margolis have noted that rigorous studies are inconclusive as to whether they actually offer any real benefits."
Liebowitz, Stan; Margolis, Stephen E. (1990), "The Fable of the Keys", Journal of Law and Economics 33 (1): 1–26, doi:10.1086/467198