I see what you mean. I have not heard the Nait50 much at all just a quick blast or two but I did think it harked back to the older Naits.
I can remember the first time hearing the original Nait in the shop and was taken aback by all the musical goodness contained in such a small package. They sounded great. To die-hard Naim fans they were not always an easy sell as many were suspicious/uneasy about an integrated design. They were easier to sell to new Naim customers but of course being Naim they were not that cheap compared to some of the competition so a fairly premium product.
I never owned one myself as I was firmly in favour of the pre and power amp being separate and had been since my first proper HiFi setup with a Crimson Elektrik 510/520 and was also a big Quad fan at the time.
I am less biased toward the pre and power setups these days with several really good integrateds out there but old habits are hard to break too.