Yeah you can compress ut3 files on the redirect.  I tried that but didn't have good results.  The map files are pretty welll compressed by default.  The compressed files weren't compressed like they were in UT99 or UT2004, sometimes the files ended up larger.  Then there were problems with the client trying to request the files.  I'd setup the compressed files and set the INI settings but some clients weren't requesting the .uz3 files at all.  So I decided to just make them all uncompressed.  I may try again with the new patch but right now I think we're fine with it uncompressed.