Sync once, be done! If your husband wants any other music, he can simply open iTunes from his iPad and buy what he wants to listen to. It will then be added to his collection. If he wants it backed up to his computer, you can do it for him. I don't see why he couldn't do it though. After it's set up initially, all he is doing is plugging the iPad to the computer via the connector it comes with. ITunes automatically opens and it begins to sync. No work from the user required. Ghats pretty user-friendly if you ask me.
As far as the Xoom goes, I can't wait to get mine. I have an iPad and iPad 2. Love my iPads, but the Xoom will be a fun new toy to play with!
P.S. I think we have the same husband! lol