Does it sound significantly different when the partials don't get dropped? Maybe it was just sloppy transcribing from some sheet music or another MIDI device that was rearranged for MT-32 without worrying about polyphony?

The music of MI1 was composed with and for the MT-32. I wouldn't be surprised if it was also the case for SQ3.

(Going off memory atm)
(MUNT) Space Quest III didn't have any large change (mostly intro). Maybe a little cutoff here-there.

At one point (where Roger is beamed up), 32 partials = 'simpler' tune vs 128 partials = packing a room with similar orchestral sounds (not reverb but volume maybe?). Or maybe depth? Can't explain this but I have to compare again sometime.

(MUNT) Monkey Island had enough instruments noticeably cutoff during the title theme. I think I've read someone mention this too with MT-32. Sound is smooth flowing with 64 partials.

I suppose using 128 partials won't hurt. Thanks anyway - the transcribing note is an interesting thought.

Using a newer MUNT + DAC = pure has changed around the results a lot. Both versions are very similar now, without the side-effects I remember earlier.

So it's a pretty moot issue for me now. 😉

You can check out the ogg comparisons here though:
http://www.sendspace.com/file/xup3u0