It would be great if a group channel could collapse into two “child-tracks” of mid and sides.
Then we could use whatever plugin we want on each signal path individually, and not be bound to use specific one’s that support m/s.
I just use Voxengo MSED to swap between M/S and L/R as I need. That’s free.
But that approach does hog insert-slots (one instance for encode, another for the processor(s), another to decode). So sometimes I use DDMF Metaplugin to host MSED and the desired (VST2, VST3 or (on Mac) AU) plug-ins.
I’d love to see something Metaplugin bundled in Cubase to enable more complex plug-in routing. And to allow it to make available as many ‘sidechain inputs’ as you wanted. That would solve this problem and soooo much more besides!