Damnit, forgot about the rear ports. Didn't realize that they made incremental improvements outside of the version #, and that v4 has already been around for 4 years.

I keep coming back to the 8-ohm vs 4-ohm thing. Seems like such a bonus that the 180 can pull twice as much power from the amp vs the 160. But I suppose that only matters if you're looking for huge SPL.

Axiom M5HP VP160 M3 ADA1000
Anthem MRX 720
SVS SB-3000 (dual)