At least they are legal here (with a federal tax stamp). I haven't shot one or even shot at a range next to one, but I'd be interested in seeing what they can do. For deer hunting it would be tough for me to go subsonic, but like I said, I don't have a feel for how much they reduce sound (sub- or hyper-sonic).

Waterfowl would be nice, but in my understanding going subsonic there you need to go up in shot size (and shoot close), so the BB max size limit would be a problem for geese where it would be really interesting.

Anyone have any actual experience to share?