Yeah, exactly...differentiate between things to control directly and things which can be left alone, and treat the array of 'control-required' modules as sort of a surrogate control surface. Always works. A lot of people don't think out the ergonomics of what makes a synth an actual instrument, but you seem to have the specifics of use down. Nicely done!
You're going to dig the Keystep with this...I used to control the Digisound with either the CV output from my ARP 2600's keyboard or, alternately, with an MC-202. But this thing is like mashing both of those together and then some! And UNlike those...it's dirt-cheap. Maybe consider something MIDI-ish down the road that can deal with USB MIDI (Expert Sleepers FH-1, for example) and get twice as busy with BOTH control signal sets...