I’m not too worried about not being able to completely mute the audio with Blinds. It’s not really designed as an audio mixer, anyway.
As you say, Shades works pretty well as an audio attenuator in uni-polar mode, but in that scenario, the centre detent is actually a hindrance.
I think the issue with using the centre detent in Blinds was that the detent wouldn’t necessarily line up exactly with an exactly 0V output. There’s a warning in the Blinds manual to the effect that the 0V point isn’t necessarily in the exact centre of the pot’s travel, so it makes sense not to have the detent.
I agree it would be handy though, if the detent could be guaranteed to always correspond to 0V.