I'm with Wolf---the Dolby C in my BX300 is great. The deck is great with metal tape (I've used TDK and Sony), by the way. But the BX series Nak's design has a flaw---it's transport is not the most robust. I believe the CR series Nak's may be the one to get.
Dolby NR encoding - did it ever work
What I mean is, if you record something with Dolby NR engaged, the sound should have the high frequencies boosted and the noise floor unaffected during playback without Dolby NR engaged. I had a Kenwood tape deck that would reduce the noise floor during recording, which isn't right. I am considering buying a new, collectible tape player.