anjohl: Aliasalpha, to nitpick: Off-key would mean in a different key than the one intended, IE, in the key of D when you should be in C. MIDI is just a way of producing electronic sound.
Aliasalpha: And with the exception of professionally made ones, I've never once heard a midi that was remotely close to the right sound
All MIDI's, if transposed correctly, will fundamentally be identical. The only difference would be the use of techniques in the original that are not easily transferred over, such as a "hammer on" in a stringed instrument's melody, or a tapping sequence.
Still, most MIDI's are note-for-note recreations of the original piece, and are in every concievable way a version of the same song.