Played both today, and I have to say that I'm impressed with both amps.
The Superchamp is good, but I really liked the VOX better. The nicest feature of the VOX was the attenuator that can turn down the power. I could OD the tube at lower volume and still get the good break-up.
Pros for the Champ:
Acoustic simulator (but that's why I have an acoustic guitar)
More selection on effects/amps
Speaker out (to hook up to a cab...but I don't really gig much...or at all at the moment.)
Pros for the VOX:
Price ($50 goes a long way for me these days)
Attenuator (can't wake the baby...

)
More Max power (for when he's already awake

)
I'll probably end up going with the VOX, because all the extra features I'd get out of the Champ are really unnecessary for me. Plus, like I said, 50 bucks is 50 bucks. I didn't really notice enough difference in sound between the 2 models that one really stuck out...they were both actually quite nice.