Okay, so it's great that rsync has built in compression that can be switched off for known compressed file types, however there is still some extra control that could be useful for tweaking when to compress files.
For example, in my case I know that all of the files over 750mb on my machine are mostly movie files; obviously I can add file-extension for these, but there are quite a lot of possible movie file wrappers, so it might be easier if I could disable compression over a certain size, as this would also exclude things like disk images that are probably compressed already and so-on.
Likewise a parameter for skipping compression on files below a certain level could allow tuning for files that aren't likely to compress well enough to be worth the effort.
On a somewhat related note, I think that --compress-level really needs more detail, such as the default compression level, what the possible levels are, and what the implications are. I believe rsync uses zlib which means values of 0 (none), 1 (fastest) to 9 (best) but is rsync's default the same as the zlib default? Should it be? Which values give best mileage in common situations? I dunno, just seems like some of these should be touched on in the man pages.