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.
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...