e bow
sorry, but i own and have used an e bow extensively both live and in the studio, and i feel its the best sustainer/feedback device of all mentioned.
its cheaper n less trouble than the sustainiac, its cheaper n doesnt require installation and routing like the fernandes sustainer and it is extremely controllable. i dont know why the e bow is considered impractical or unuseable. threadstarter pm me if you'd like to give an ebow a try i'd gladly meet up with you n let you check out mine.