Yeah, the miner mask is different in the SNES version. Actually, I think what happens is they fix the miner glitch in the SNES version, which in turn would affect where the terrain masks are drawn.
I checked the basher's mask in the SNES version and to my surprise, discover that it is in fact the same as the Genesis and Amiga versions. So it would seem that the difference has nothing to do with the basher's mask. I would need to observe the Genesis version more carefully to see what is going on. It's possible that maybe one of the tricks (which I often called the "Mayhem 10" trick) I rely on for the solution simply doesn't work in the Genesis version, I'll have to find another level to check. Even so, I still expect lose 2 to be possible but I couldn't even achieve that on the Genesis version, despite appearing to have done everything the exactly same way I've handle the SNES version.
Fortunately, thanks to savestates, I think I can at least do side-by-side comparisons and see if I find the crucial difference.