One thing is clear though. ITunes Match and the matching function of AM aren't the same. I'm using the latter. My music that has been found to already be in the AM catalog become indistinguishable from those tracks in my library.
From what I know Match uses sonic footprint, then removes the expletives. AM matching only uses the song title, then matches it with whatever is nearest the AM library, ignoring additions like (live), (demo) and album titles. Well done Mr Cue.