This got me thinking. Right now different # audio channels are considered different recordings, even when they are otherwise the same. This would at least address that specific piece of the problem with recording fragmentation.

Since format is usually handled per medium, it would probably make the most sense to have it handled at the medium level in the release editor. Basically, either automatically where possible (based on medium type) or manually, you would set the format of tracks on that medium, right alongside selecting the medium: mono, stereo, quad, 5.1, etc. "I don't know" would definitely have to be an option too. (Oh, and I see there have even been 3-channel recordings...)

That would allow one recording to be used for multiple formats. On the recording itself, you could have icons for 1, 2, 3 4, 5 or something like that, or just different sections (like with release types on an artist page) that show where the recording is represented in the database in different formats.

This could possibly work with videos, too, although you'd have to allow adding video-related relationships on recordings that are also used for audio-only formats.