I was in the same boat as you, although I couldn't switch to Firefox - it was way too slow. I ended up switching to Chrome - with three plugins (Speed Dial, Smooth Gestures, RSS Subscription Extension), I was close enough in feature parity to be happy. The only thing I'm really missing is that Opera would not close when you closed your last tab, but Chrome does. Everything else works about the same (other than no built in e-mail, bit torrent, news, unite, etc.), but that one still bothers me.
The nice benefit - more sites work in Chrome, and Chrome feels a tad bit faster.