There doesn't seem to be any way to fix this. In addition, we have no control over getting older, dynamic masterings replaced with newer, sometimes dynamically-squashed "loudness wars" versions. Match also seems to not always be able to recognize alternative mixes as separate versions. I even tried to Match Steven McDonald's "Redd Blood Cells" project (where he added bass to the White Stripes' "White Blood Cells") and sure enough, some of the songs are being "matched" as if they were the original White Stripes album. This would be workable if there was a way to override it, but there doesn't seem to be. So, if you can't get Match to work, you simply can't listen to the music in question on your device. And that's a problem.
And the 96 kbps limit is a hinderence if you have any early 20th century music, as that's often ripped in mono at lower bitrates (80 kbps = 160 kbps stereo, after all, and the dynamic range doesn't really require more to sound good). So: seems like there are lots of problems for anyone who's not just trying to sync up their smallish mainstream collection. Or for someone who fits that but has something like the Beatles in mono.
In addition, there are lots of errors that are problematic, especially with a large collection. "Duplicates" that just aren't duplicates, for one. "An error occurred" on a lot of tracks, that you have to find, go back in, and try to submit to Match again (if there's an error, why wouldn't iTunes try to process the track again itself? Is anyone EVER going to say "oh, okay, I don't need that track"?)
Anyway, I'm really not seeing this as ready for prime time...
iTunes Match found several matches for tracks from my Beatles in Mono box set, but those matches turned out to be the stereo versions from the iTunes Store. For those of us who actually care about the recording and not just the content, is there any way to fix mismatches like this? If iTunes Match decides that a song in your library matches a song in its store, is there a way to correct it if it's wrong?