+ 1 to the slide pedal question. It sounds very well controlled by Dweezil, and a lot of guitarists would probably like to have enough expression pedals in a rig to be able to add that. Wouldn't replace a B-bender though (uses the players body to whammy up just the B string); I guess its too difficult to algorithmically single out a note range from the Axe Fx input, so you could do a kind of Super B-bender effect. In other words you could set an effected pitch range, and maximum pitch shift up range, and so effected-range notes would be pitch-shifted whammy pedal style by the expression pedal - say by a whole step if that was your shift-up setting, but notes out of the effected range would not.....) One could therefore use this for more than the B string. Example, you set the range from the pitch of the E on 2nd string to the A on that string. So any time you play one of those notes (on any string), and others outside of that range are present in the Axe Fx input as well, and you depress the expression pedal, the effected-range pitch goes up, according to the shift range. Meanwhile we could give donations to the B-Bender guys so they don't don't lose any income. OK, maybe that last part should be taken care of by Goldman Suchs.
