Hi Jim,
Thanks for your reply. It's very instructive. I did consider the 1cm limitation of 2hp. The buttons won't be very helpful, indeed. But since the notes will be coming from the Torso, I don't really mind.
Aside from that, yeah, you're right. There's several pieces missing. The stereo mixer just isn't a good match for a mono system. When in my home studio, I can plug it all into an audio interface and add stereo imaging any way I want to anyway. And you're right - the VCO-filter-effects flow needs a lot of work. I'm playing around with VCV Rack as we speak to learn more about that.
As for the Mantis - I like the suggestion. In the home studio, I have another 3U space for another 84HP for extension. I was considering the ES9 and some stuff I may not always want on the road for that. I built my own racks with that in mind. But I'll reconsider, because I read a lot of positive stuff about the Mantis.
And I have noticed it's probably a good idea to start off with 1 voice and to really understand what combinations and patchings are possible, before upgrading to several more.
Peter.