Thanks for the responses guys.
I should quantify my post by saying that I will pretty much exclusively be using the high gain channels as old wrist injury (I stopped playing for 10 years) has me restricted primarily to power chords. I attempted to get back into guitar playing many times, but swelling of my hand and wrist prevented me. Once I realized that I mostly enjoy playing mainly power chords songs (Greenday-esque) I decided to grab my axe and have fun on the couch (no pun intended).
I A-B'd a 40xl with a 80x at a local shop, and found that the 40xl was a "little fuller". However, they didn't have any 80xls in to do a true comparison. They will be in within the next week or so and then I'll be picking one up.
I have to say, however, that I have played a LOT of modelling amps recently (Fender, Line 6, Vox, etc.) and have personally favored the cube by a clear mile. (guy at the music shop pretty much asked me to leave while comparing the amps, as he thought I was disturbing the customers lol),