Yeah, I've offered him my F5, which is basically done, but will need a few small modifications for speakers (just has K1000 output now).
Most likely he'll get the PASS integrated though, and have a one box solution. Source is another story all together.
Craig, whenever I finally build my own house, I will build a large subwoofer enclosure under the floor or stairway, that will vent into the main listening room. Most likely not a horn, but a seriously large enclosure, with 18" drivers.