Just listening to youtube, I think I like the way the arcade music sounds more than the SNES version, but that's just me.
I'm actually upset at myself I didn't get the remake when I could. I knew that people were hating on it then as they are now, and it could all be true, but I still with I bought it because I've never played Turtles in Time. I have the original Arcade game on XBLA and NES, at least.
Oh, I have this too! Maybe it's time to bust out the NES Advantage...
edit: from what I remember hearing, Castlevania 3 JPN is easier than the one we got in the States. I don't know any specifics, though...
It is. My review goes into detail about the differences.