Thanks for your input! I've switched the Uscale2 with the first edition and added a double multiplier.
The SQ-1 is an external device and I really want to keep the system as simple as possible, e.i. just the rack and a mixer.
For example the Soundcraft EF12 is an analogue mixer with Lexicon effects and 12 mono inputs, which should be enough to create a coherent, musical, mix. So I actually don't even really need the delay module, but I'll leave it in for now.
This drum rack is going to be a unit in a bigger system which may have dedicated line-outs for each voice, with a maximum of 12 voices, but I'm still not sure if that's feasable or necessary.
At least now I have a proper starting point. If you have any tips or suggestions, I'm all ears!