Incremental improvements are made throughout the lifetime of a version. My sense is the v4 is now fully baked.
If you look at the impedance chart, it's 4 Ohms in limited bands. You'll be very happy with the 160.
If not for the >2" height difference, I'd be totally set on the 160. I've got 62" of wall height to accomodate a 65" TV (33" screen height), the center channel, and a media stand, so it's gonna be tight.
I ended up calling Axiom this morning and Ian happened to answer. He confirmed that there were no incremental 'tweaks' on the 180v4. While I'd be under-utilizing a 180 in my setup, he saw no drawbacks to using one vs the 160. I also asked about the rear-firing ports and he said 2" from the wall should be sufficient (and port plugs are always an option if needed).
Still unable to make up my mind, I opted to order both, with the option of returning one.
