It's actually worth noting that I did this on the Thinkpad that I use more often than any other computer. Whichever keyboard I'm using the most is the easiest one to use, whether it's huge or tiny; switching keyboards will inevitably slow me down. I'd guess that if you put me on an unfamiliar keyboard, it would be 90 - 100.

I had a summer job taking medical dictation on an IBM Selectric. Foot pedal controls on a dictaphone! It was such wonderful and mindless work, and I kept getting to write down fun long medical words. Best summer job ever. Well, best menial summer job ever.