My question for you (other than how they can coexist)
They can, but they should be installed to different directories, and will need different db_dir, admin_root, and port.
is whether it is worth it for me to switch to the nightly…I don’t use flac or any of that – just have a 60gig music library (all mp3) that I want to serve up using iTunes and a couple of Soundbridges. Will I get much benefit from using the nightly or should I stick with what I have working?
I’d say if it’s not broken, don’t fix it. Although the nightlies are a lot faster against a soundbridge. If you aren’t using anything else the nightlies give you, then that’s the only thing.