My son shoots three under with his Kanati, which is tillered for split. He shoots right at 10 ggp, and I don't think his bow makes any more noise than mine. I've experimented with a bunch of bows and found that some are loud when shot three under and some aren't. Tiller didn't seem to be much of a factor as all but one were tillered for split. The one tillered for three under was louder when shot three under...go figure. The bottom line is some bows are louder when shot three under and some aren't. I don't think tiller is as much of a factor as general design and materials.
As several have said already, you would most likely be wasting your money. If your bow shoots well and you shoot at relaxed deer, you shouldn't have a problem. If the deer is alert and skittish, it will probably duck no matter how quiet the bow.