I recently had a chance to play with a friend's Digitech Whammy and when I'd shift the pitch there would always be a muddled, slightly off-pitch quality to it (especially when letting a few strings ring out simultaneously), although I think it was calibrated properly or whatever. This is probably kind of a dumb question, but how do you get a fairly clean tone out of the pedal?
Never tried one, but a mate has one of them Morpheus Bomber pedals, I've heard some of his recordings with it (including downtuned chords and stuff) and it sounds incredibly good. You should definitely check it out if you're looking for a whammy pedal or just for tuning down without adjusting your guitar. Most people probably couldn't tell if it's the original tuning or if it was pitched down with a pedal.
It doesn't track more than one string.
Peavey 5150
Mesa Mark IV
Mesa Single Rectifier (Series 1)
Fender Custom Shop Tonemaster
Roland Microcube

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Digidesign Eleven RackAxe Fx Ultra