Do you plan on having a clock source?
I would have a couple of traditional ADSRs in the rack even if you're going to keep the Zadar.
Additional utilities will eventually be on your list.
Plan to have a bigger rack than this. The amount of HP you've left yourself just won't do. Eurorack systems grow.
For the audio signal, my interface has enough I/O so it's not a concern.
I'm definitely short on attenuation and CV mixing. The Erebus has a noise source as well as one s&h and VC Amplifier with attenuator and inverted outputs. Not enough (I usually use the VCA on the Erebus for it's own patches) but in my style I rarely use all the instruments in one track so maybe I can share it for the time being.
I can send clock, cv, gates from the Beat Step Pro too.
I already have this rack so, by god, I will fill it and then move on to another rack if I need to. Im just looking at the best compromise for this rack so it's usable for the time being. Perhaps a smaller sequencer than the voltage block, which would allow me to add more utilities. I'll probably get rid of the 8hp clouds clone since, while fun, it's not essential to me.