[Richard Crowley]

"Don Pearce" wrote ...
Everybody is clearly reading this question differently to the way I am. If
the question is "Would it be a good idea to have an application that could
rescue a tape recorded in B/C when a proper playback system is
unavailable?" Then yes, I can see that it might have some limited
application for a while.

But that is not how I read it. My understanding of the question is that it
is asking if it would be a good idea to routinely offer Dolby B and C as
companding methods in a DAW, on the basis that they might offer some sonic
advantage. The answer to that is a definite No.

Yes, of course. It would be absurd to try to use any kind of traditional
Dolby noise reduction when recording digitally. Which is why we all
jumped to the obvious assumption that the OP was talking about the
decoding of previously recorded tapes. Admittedly, that assumption
should have been explicitly stated.