Personally, I'd skip the NHT Super Zero 2.0 due to the lack of bass and need for a high xover. Many people use 100Hz, but that is too low IMO, based on measured response of those speakers and Audyssey results of the speakers in my room.
The Absolute Zero however, doesn't need that high of a xover. Unless you are demanding high SPL, it should be comfortable at 90Hz depending on placement and SPL demands. I owned a pair for awhile, and I never found blending with a sub to be an issue.
The Absolute Zero is a nice little speaker, and IMO, much better than the SZ 2.0. That said, some could find the AZ too "clinical" sounding, where the SZ 2.0 sounds more relaxed, at the expense of being less detailed.
I also had the PSB Image B4 for awhile, and in my experience, the AZ plays deeper than the B4... at the expense of needing a little more power to get as loud.
The Image B4 does play deeper than the SZ 2.0 though... and is also easier to drive. It'd be a clear pick over the SZ 2.0 as well for me...