The only time I've seen UFS having an advantage over HFS+ is in compiling PHP: there's a file and a directory called pear and PEAR that's legal in UFS but not in HFS+. It's not a big deal, though, if you don't need pear (I don't even know what it is!).
HSF+ has the advantage of supporting traditional Mac aliases that follow the original file around when you move it whereas UFS only supports the *nix-style symbolic links that break when you move the original.
Ouch.
I didn't try this before. Guess I'll have to reinstall my OS X once again and switch to UFS.
There are lots of (unix) apps out there that require a case sensitive file system.
And the concealed waring in the developer doc about different file locking behaviour between HFS+ and UFS seems to spell disaster as well...
*Sigh*
I do not suggest doing this. OS X is magnitues of order slower on UFS than HFS+
If you must use UFS make a seperate directory to put your source. Personally I would just hack it to make it work on HFS+ then everybody can compile it.
I think UFS is case sensitive, whereas HFS+ is not. So whereas in HFS+ you could have only one "My Document.doc", in UFS you could have "My Document.doc" AND "My document.doc".
I've also noticed that UFS seems to have issues with Classic installation. I couldn't make Classic run perfectly with Mac OS X on UFS. I don't know why, though.
I'm back to HFS+ since I still wan't to be able to recover files from my Mac OS X partition in the unlikely event that something does happen to it.