Well ......... I did 'measure' with a piece of paper and the Tyros keys ARE smaller (width) than the SD1 keys, about 0.5 to 1.0 mm.

In my (limited ?) view, for example the SD1 has the standardized piano/organ key-width of 22.4 mm.
I dislike the Tyros key-feel, 80% caused by the non-standard size. The other 20% caused by a non-weighted feel and limited vertical key-movement. (like accordeon-keys)

Realize this is my PERSONAL opinion, others might have a totally different view D:

Roel