I wouldn't hesitate to use an AxeFx on stage; I'm not as picky about digital tones live than I am in the studio. The way I see it, is if you have the time and resources to get the best possible sound you can for something that is going to become the definitive 'sound' of an album to be played back to however many people buy the record, you'd use real amps, not imitations of those amps. On stage, who gives a fuck, the Axe is definitely close enough there.