Hi Rikki:

I did owned not just 2 SD1s, also a X1 too, well, the midi file re-voiced in song setup in the SD1+ has only the instructions of those changes only for the Ketron, but the midi file remains unchanged unless you remaped the voices an d controllers in the PC with any secuencer program such like Cake/Sonar, etc....I did changed the few midi files I did use in it, but in the PC, I also find that I have more control even in the dynamics, fx, etc...
As an example for my own experince is:
in the Reverb (control 91) to have a decent reverb in the SD1 you must set up at least 100-127 value(from 0-127), but in the case of the Yamaha Arrangers like the PSR3000, T2, you need less, around 50-70 depending on how much FX you like, each manufacturer FX procesor has diferent sensibilities, also may I point that also the note velocity response is diferent, I have to lower it if I play a file in the Yamaha, somewhere 50-80 note velocity range is ok, more, sounds overdriving it, but velocity ranges between 100-127 are just fine for the Ketron.
Needless to say, I do recomend to make the adjusments to each midi file in each track in the PC, well, at least I do it like that, perhaps because I am very picky.

In the drum maps, I still use the PC, because sometimes you get a file that has an annoying clap that should be a snare ( as an example), that, only can be remap in the PC with the Piano roller mode, is a very fast procedure, this is not posible to do in the SD1+ yet, only change the drum kit and volume, fx overall.

Or you get a cymbal that is a little to loud, or the hihats to low, well, I use the Cals (Bustdrum), so, I make the note velocity adjustment and that is it.