Put a few VCAs back in. Right now, you have sort of 4 1/2-ish, and while these deal with the audio aspects nicely, you have no VCAs for dealing with modulation and/or CVs.
Lose the '07 Mult. If the O&C's quantizing is driving the VCOs across all four channels, you don't have enough modules on each channel to require the buffering.
The flow on this build is sort of odd, actually...there's things up near the VCOs that would probably work better by the mixer, and vice-versa. For example, the Mir...it seems like it would be optimal for controlling and summing levels from your four VCOs, but it's not located in a row that's convenient to the VCOs themselves. Whenever possible, try and keep your patchcord lengths short as longer ones can pick up electronic crud more easily.
As for filters...you might look at G-Storm's stuff, most notably his ARP 2600 4012 VCF clone. G-Storm's VCFs also usually have the convenience of dual input mixing...very convenient!