Hi John,
If the range of 'sound variation' is not too different in case of different parameters, then the normalized internal range is a good idea. On the other hand, using the original ranges is more straightforward and you can do the required transformation from 500 to 63, for example,, in the sub-routine. But, in some cases a different internal velocity curve may be required. This can be programmed later, in order to normalize the user experience, too.
... Now, it occurred to me, if I don't remember wrong, that pushing and rotating the 01X enconders, increased the speed a lot. Double function encoders like these can be quite useful in many other purposes, too. Sliders, on the other hand, are sometimes better, because they allow you to see and visually remember the settings. And, you can change 10+ parameters at the same time with your fingers, instead of rotating only two knobs at a time! I think that's why Korg selected them in their M3 keyboard instead of the knobs (not endless rotary) used in their earlier Karma keyboard.
A different kind of parameter control (just for 'brain storm'):
http://www.vintagesynth.com/roland/pgs.shtml#pg1000
With a PG-1000 you can change all the parameters of a D-50 keyboard as well as the D-550 rack module! The size of the PG-1000 controller is approximately 40cm x 30cm x 4cm. The sliders cannot ofcourse replace endless rotary encoders.
...
Recording parameter changes could be a useful function in order to make the sound more living and performances repeatable. Maybe this is something that can be done already, or, is better to leave to DAW.
Cheers,
Tiitu.