I still record with Dolby B, for me it sounds great! C can introduce audio pumping which is really annoying! Not used my cassette deck for a while.....have taken a bit of a break! I do have some nice boomers to repair/restore that I bought last year, I may get started during Autumn/Winter as I tend to stay in more!!
" C can introduce audio pumping which is really annoying! " I have NEVER experienced "pumping" with any form of Dolby Noise Reduction, only with dbX. Perhaps your experience was with a deck that was not properly aligned, as Dolby C is very sensitive to this.