I just came across your post. You seem knowledgeable. I hope you don't think the Model 50's low frequency stops abruptly at 42Hz. Since the second line in the specs is : Bandwidth: (-10 dB): 28 Hz - 20 kHz. That means, with room reinforcement, the Model 50 can provide usable bass output down to 28 Hz. By the way the Model 50 is a double transmission line speaker not a ported speaker. What should also be noted is that the Model 50 is time coherent and, with the woofers wired in series, it is powerful a point source without the Doppler effect that can occur with large concentric drivers.
NSMT or Zu?
I have a Hegel H120 integrated (75 wpc) and am considering new speakers. My room is large so efficiency is a consideration, budget is about $3000 max. Am looking at the Zu Omen II and NSMT. NSMT is intriguing but also confusing as they have so many options in the price range (Model 15, 25, 50, ?) Thoughts? Experiences?