interesting, how is this working? are vcv rack instances sharing same address space? … a quick look at the code, makes me raise questions about thread safety ?! its pretty common for daws to place different ‘tracks’ on different cores, so this would be more important than for example using in standalone vcv with one processing thread.
side chains the method I employ, are of course a daw feature so are guaranteed to work 
thats just feature of having 16 midi channels 
whilst I like having midi output for generative features… I really don’t want to modulate via it… thats kind of what we have CV… thats why I love modular. I cannot really see lots of people using a lot of midi cc for this purpose…beyond a few its going to get a bit laborious. also consider that to get midi cc into ‘the grid’ you have to use modulators… Im not every sure you can create 128 modulators, and if even if you can, it take you a long while to actually do it, and make use of it;)
generally, I think the amount of communication between different instances of Poly Grid and VCV instances will be limited…
but hey, we all have different needs at different times. I wasn’t saying Live or Bitwig was better… just they are different.
in terms of M4L/The Grid, they aren’t even really comparable… The Grid is much easier to use, really possible for end-users to use. but M4L can do a ton, that just isn’t possible … eg. I can create my own M4L (binary) objects.
so you pick whatever tool works for you the best for the project you are working on…
so vcv rate vst is declaring these as stereo channels, which is why all hosts are seeing them as stereo rather than mono pairs. (this is not unusual, whist the vst standard supports strereo/mono channels and ‘speaker layout’ its not widely used)
but you can treat them as mono.
(its not really an issue since the daw is throwing around stereo buffers anyway ;))
one interesting point, is that of course you can reuse these outputs across multiple grid instances.
you can also of course in one grid access multiple vcv rack instances
EDIT: I noticed there was another topic talking about the use of Teleport … so Ive posted on that (more specific) topic , why i think its not safe… and Id not recommend it see my post here