We've been listening to the NX-Otica's, NX-Treme's, NX-MTM's since we cut the first pairs way back in late 2015/early 2016.. Have heard them in a few different rooms ranging in size from 18x12 to 40 x 18, with subs / without subs
If youi are in a room anywhere near the 18x12 range, you are going to be in that flat to 40 area and with 8 of the M165-16's, you'd have no issue adding a little dsp boost and getting them flat 30. We've done it with the NX-Otica's and the M165x 8's and it worked well, there is a thread I started on that where other's jumped in with similar results ( including Ron I believe)
I had the OB7's prior to Otic's which 4 of the M130X drivers in a sealed cabinet and I was pretty shocked at the speed and impact of the 4 M165X woofers we used in the NX-Otica's.... I will never go back to sealed bass unless at some point I had the space to try a swarm setup and compare... not likely anytime soon.
Not a huge difference in floor space from a pair of sealed servo subs to a pair of dual h-frames.... just something to think about
jay