Here's the rig that I ended up actually building:
Here's a track I created with it:
Thoughts so far:
I wanted something that I could use to do ambient generative music as well as be controlled from midi, and also have a line in so I can use it for effects, and I succeeded on that score. I have an analog audio path from VCO to VCF when I want strictly analog.
As I mentioned above, with the constraints I have, I knew I'd be in for some cramped controls, but I put a premium on getting decent-sized knobs for the controls I'd be riding the most. My soundsources go into the 3xVCA so I use it for mixing as well as applying amplitude modulation, so those knobs are are important, and I'm happy with that module. The knobs on Disting work great for me and I'll be using those a lot. The frequency knob on C4rbn is borderline adequately sized. All the little knobs are fine...either I don't access them often or precision isn't required for them. One thing I'm finding valuable is cables with an attenuator in them. That way I don't have to waste valuable hp space on simple CV attenuation.
Stages is a gem. I can use it as any combination of: quantized pitch controller, LFOs, envelopes, sequencer, slew limiter, etc.. With a small rig like this, every module must be able to do multiple jobs and Stages is priceless, especially with the qiemem firmware.
I have a little space left. I'm thinking Ochd would help me with all the slow unsynced LFOs I need for subtle movement and would free up Stages segments to be used for other tasks. I could use another tone generator, but Disting might be useful for that, in which case I'd need something to do effects processing I'm currently doing with Disting. A utility module would be handy for creative signal mangling. Any suggestions?