You can do a lot with just four 12π hornsubs. I'll let people using them respond with comments on what you can expect from them. That way you can hear what other people say about subjective sound quality and things like that.As for technical details and specifications, the different versions are more alike than they are different, but the latest version is a little easier to build and has the smoothest response. Even with just one box, you have nice deep, smooth response down to 30Hz with very low distortion. It's even better when you have four or more. Measurements show the 12π hornsub is about 10x more powerful and has smoother response than most other subs, and has about 10x less distortion. I'm very proud of the performance measurements of this subwoofer.
The 12π hornsub is a large cabinet, but it is surprisingly easy to move with the right equipment. The wheels are placed between the ramp rails of a 16' or larger truck, so two guys can easily roll 'em on and off a truck. You just rock them back on the wheels using the handle, and one guy pulls from the handle while the other guy pushes and directs from the mouth side. You can fit twelve of these subs in a 16' truck with lots of room above the subs for other gear.