Keeping multiple versions of a program for the sake of old technology make this a dream. Anything in the midi standard can run 32 tracks on a Pentium or less, probably even a 386.
It's not been updated, and it's limitations are severe. I'd suggest finding out the very best midi compliant keyboards for which there are patch maps and buying those as the prices plummet.
The 'I gotta have midi' guys seem to be mostly the ones who want to make a backing track sound exactly like the original, program all the signature licks. One band in town has an older guy who is still using Atari and has duplicated stuff like Brittany Spears and the guys come on with the lead singer dressed in drag right down to pigtails and the song sounds amazing. But what's the market. I hired them for a convention, 5 guys and had to pay 700 bucks for two 45 minute shows. That was 7 years ago, but now that has to be 1200 or more. They get 10 gigs a year I hear. So your income is what?
Roll your midi track for Chestnuts Roasting, and I'll roll a backing track with RealTracks. My work will take 15 minutes. And then we get them 'tested'. I think PG with RealTracks and John pushing buttons is going to blow the midi out of the water, especially if we say you have only 12 hours working time to produce it from the same starting point.
I have a lot of midi. EWI gizmo, keyboards, a big Yamaha organ in the garage with midi on it, 2 external midi modules, but I use them less and less. The Ketron SD2 is great, but I don't think I've used it in 6 months and it's hooked to Band in a Box and once in a while I click the melody on to check something and I tweak a note, but then I shut it down again.