I have tillered bows with a band saw and experimented with it quite a bit when I first started,,
now I don't feel I can go any faster with the band saw than I can with a good sharp farrier rasp,, and I feel I can see what I am doing better with the rasp as well,, if I tillered with the band saw then I have to even it up with the rasp,, if I tiller with the rasp, then I don't have to even it up,, so actually I think it saves me time with the rasp,,, no doubt that roughing one out with the saw is time saving,, but the tiller I think the rasp wins,,
working with the rasp forces you to follow the taper as you turn the bow from side to side,,in the end I think it gives you a better tiller,, the better you get at tillering you more you realize there is no easy or faster way,, I have owned all kind of sanders etc,, and I still prefer to tiller with a rasp,,,I have more control,,, and I like that,,