Good point. I think for some games the FM soundtrack sounds better than the MIDI version. If you like OPL-FM music then you see it through a different light.
was there a specific device in mind above all others during composition?
It's kind of hard for me to answer this objectively, but in terms of compatibility I think Descent's GM soundtrack is as plain vanilla as it gets. It sounded great across all wavetable sound cards (and external synths) I've had. At least for me no card sounded better than the other. Guess I should clarify I am talking about the game's excellent MIDI compatibility, not the wavetable quality of the hardware.