I had the memory installed and played with it. But didn't have anything amazing in terms of custom stuff. As I recall it had several synth wavetables as standard. I vaguely remember being able to choose between MT32 and GS (and maybe something else too) giving somewhat different sounds to each "instrument" available.

I know if I loaded a midi file, to get the best sound you'd often need to choose between those options. But at the time, I knew very little about the technical side of the midi capabilities.