Winslow Burhoe was the speaker designer for Nuance. He's bounced around quite a few companies in his career (EPI, Boston Acoustics, Acoustic Research, and API/Energy). He strikes me as an old school engineer, his website mentions nothing about the NRC or the family of curves.
http://directacoustics.com/?page_id=56But he did get results. I bought the M22ti in 2006, and all it had to do was equal the midrange and treble of the 330's (I wasn't expecting a bookshelf to have the bass of a tower). Instead, it wasn't even close, and I returned the Axioms.
The Kanto Yumi's I bought in 2015 sounded different from the 330's, but I considered them equals. The M5HP is the most neutral loudspeaker I've ever owned, and there's no going back. But I don't dismiss anyone who ever bought a Nuance speaker package in the 90's, they probably overpaid, but they got good Canadian sound for that era.
And returning to UK_AV's question, a 5.1 system with multipolar surround speakers would be fine. I have my tripolar Angstrom Suono 100SD's on the floor 110º from the front, and it works great. I don't have experience with Atmos and would defer that to someone else.
