X68000's are basically the Ferrari's of the computer world. When they are well cared for, they are beautiful. But buy a cheap one that has been in the back of the closet for 20 years, and you got some work to do. My XVI was serviced by someone who knew what they were doing, and has been rock solid since the day I bought it. Still though, emulation is decent enough and you can use real MIDI modules with the emulators. X68000 is by far the best reason to own a CM-32P/64.
Quite a few games were meant for the 64, and even more for the 32L's extra sound effects.
Choujin and Gemini Wing are the only two games I know of that support the SN-U110-PCM expansion cards.
There are also some cool music tracks that use them as well, if you search hard enough.
Modules: CM-64, CM-500, SC-55MkII, SC-88 Pro, SY22, TG100, MU2000EX, PLG100-SG, PLG150-DR, PLG150-AN, SG01k, NS5R, GZ-50M, SN-U110-07, SN-U110-10, Pocket Studio 5, DreamBlaster S2, X2, McFly, E-Wave, QWave, CrystalBlaster C2, Yucatan FX, BeepBlaster