When I was using tape, I always used Dolby Noise Reduction, as this was by far the most transparent of the noise reduction system. However, for it to work, the tape machine had to be meticulously lined up before every recording, which is the main reason I stopped using tape as soon as digital recording became available. In the studio, where we used Dolby A noise reduction, we lined the tape machines up every morning, and as there was no aircon, on hot days we might check the alignment after lunch.
At home, Dolby B was OK, but Dolby C noticeably better but required even closer alignment especially of line in to line out levels which had to be well within 1dB.
So many of the criticisms of Dolby Noise Reduction were entirely due to tape machines (usually cassette) which hadn't been aligned to the specific tape in use. It's hard to maintain 1dB alignment as even good tapes like Maxell or TDK had that sort of variance batch to batch, so unless the tape machine as aligned for the specific cassette to be used, Dolby mistracking could become audible.
S.