Furor actually scales well with innervate whether or not you give it away or keep it. In situations where you need mana, you can innervate yourself for huge Euphoria gains (You should only need 0-1 per fight), and you can feed the rest of your innervates to healers if they're struggling with mana. Three points in furor means you'll be feeding healers 11.5% of your non-Furor'ed mana pool, as opposed to the normal flat 10%. That'll have more of an impact on healer mana that a tiny damage taken decrease from 1 player in a 10 or 25 man raid.
Edit: I think I just convinced myself to make the switch. Go figure.