Which Nakamichi to choose?

@lowrider57 

I use Dolby B, but not Dolby C. With Dolby B, there's not much to choose between a hot-rodded Revox A77 half-track at 7.5ips and a hot-rodded CR-7a.

"Hot-rodded" means mainly cap and resistor improvements, not fundamental circuit changes.

@jond 

Not my experience with the CR-7a. The auto-alignment feature makes up for any limitation in what is basically a different compensation curve. 

@terry9 I have never been fortunate enough to use a CR-7a my decks were a DR-2 and a DR-10. I have no doubt a really high end deck would be a different experience.

@jond , I agree with you; I tried it and decided against using it. I think everybody back in the day tried it and came to the same conclusion.
  I still have tapes that I recorded with "Dolby On."

It's true that the many cassette decks suffered high frequency loss using Dolby Noise Reduction, however this was not an issue with the better Naks. I have owned a Dragon, CR-7a, 670ZX with NR-200 Dolby unit, RX-303, 581Z, and still have my original 582. None had a high frequency loss using Dolby.