Yes, I want to push DOS to the limits of MIDI playing, mainly BlackMIDI (the impossible music stuff, but on a smaller scale, 200K notes and not 6.28 million for example)
Maybe I've completely misunderstood what you intend to do, but if you are trying to find a player software able to push more than 18 notes simultaneously through a single OPL3, you will not find one for any OS. It's not a player limitation it's an OPL3 limitation.
If the MIDI file you are trying to play requires more polyphony than the synthesizer can support there will be dropped notes at least. If this is pushed to extremes (like thousands of notes), the results can be unpredictable (possibly what you are seeing with DOSMID). Another player might react differently, but it still won't exceed the OPL3's polyphony limits.
I don't know of anyone who has tried driving an OPL3 in this way, but I obviously don't know everything (very far from it). That being said, if you are curious as to how the software/hardware will react in extreme conditions, you are certainly free to try all the players with direct OPL3 support that you can find for DOS. Maybe you will find one that works in a way that you are satisfied with.
Again, if I have misunderstood your objective(s)/expectation(s)/hypothe(sis/ses) in this case, please feel free to clarify.