I want one of these.
If nothing else a way to dial in a sound with my amps and mics, store it, track with that, and be able to take down the snipers and attack dogs that I put up round my mics and settings in case someone even looks at them funny would be extremely useful for me.
It would free up the mics and amp in use for other work, and it would make tracking less painful, extend valve life, all sorts of cool stuff. I want one, even if its just a decent emulator, not as accurate as it seems to be, I can reamp after tracking with it.