Yes, we used the sustainiac for the leads on BFTA. I love those things (I still own two of them). They are a large pedal unit with two pedals, one that sends a boost of tonic (root note) feedback into the transducer, and the other that sends a dominant (fifth) into it. The transducer fits on to a magnet that's attached to the back of the headstock, and is powered by a 60 W amp. So when you hit a note, then step on the pedal, a massive burst of power is sent into the neck and the guitar vibrates and occasionally screams with pleasure. All great fun. I used to run the pedal part and do the punch-ins at the same time, so George didn't have to worry about anything but playing the solos.
I think the sustainiac is made by the same people who make the sustainiac built in device, but it's FAR more powerful - the pedal that houses the 60W amp itself is a good size.
No pedals were used for the rhythm tone, but we did use a TS for the leads, at least for some of them.
Warren and George were, and probably are, still good friends. They grew up together in Orange County I think.