PS: the uZeus only uses half of its mA with this row. Is there a way to power the whole row with the Mothers PSU?
The Mother doesn't use -12V. Hence, the mother's PSU doesn't delivers that.
But the other way around works - you can power your whole system from the µZeus. The power should be sufficient.
Apart from that I like your system. I don't know the VCO - might be nice.
You can use stackable cables instead of the passive-mult. Then a braids would fit in (also not HP-dense)
And with two more HP you could get a Rubicon, if you like FM.
RYO Penta would be a even smaller 5 step sequencer with small but dedicated 'knobs' - it's DIY though.