It kind of strikes me that if the intent is to avoid duplicating the sound of the other synths, you might want to reconsider that SE 4075 filter. While the Binary Filter does have some non-typical weirdnesses, the 4075 is sort of a rev.3 ARP 2600 filter minus the high-end dullness. Having used a rev.2 for a long time (basically, what the rev.3 was intended to replace after the Moog lawsuit; the sound is similar, but with the high-end mod done to the rev.3, it's very similar to the original 4015 (rev.1 and 2) which I'm familiar with) the sound is...well, it's that old-school LP ladder sound. However, there's ways to get that and a lot more with some other modules, which could give you a lot more timbral options. Or you could rely on the Binary as the 'typical' filter and go off in some stranger directions to replace the 4075; adding something that does CVed formant filtering, for example, gets you into the general zone of things like the Synton Syrinx, a very nifty and rare device.
Don't think that 'basic' is bad...it's actually quite good unless you already have 'basic' on hand and you're trying to push a sonic envelope with the modular...which would be the right move, as modular is often about pushing the envelope. Now, one thing that could be done to get at that might be to drop the Levels and instead swap in...wait for it...FIVE 2hp mixers. WTF?, you say? OK...look at the DixieII+s for a sec. Each of these has multiple simultaneous waveforms, plus a suboctave out. By putting a 2hp 4-in mixer with each, you then get the ability to waveshape by mixing waveforms, resulting in a much greater variety of timbres even before filtering. And you still have two more left, which could be dropped in most anywhere for either audio or CV duty, since they're DC-coupled.
And speaking of DC...which sucks if you output it from your final outs...you might look at an isolating output. Happy Nerding has this 4 hp thing, the Isolator, which offers balanced stereo outs (TRS 1/4") with transformer isolation and a ganged stereo level control. You'd lose the headphone amp, but given that you pick up ground-loop killswitching plus the nice transformer sound, that'd actually be a plus. It's cheaper, also.
Maybe also drop the mults...the space you're in is a little tight for those to be onboard, plus you don't have enough voltage splitting to warrant buffered mults. Instead, reclaim a little more space and use inline mults or stackable cables like Tiptop's.
As for the MIDI interface that's there (an Intellijel uMIDI), it actually does more than this system needs, such as clocking for a sequencer, which you don't have one of in the build. If you're considering using external conversion with the SQ-1 and/or 0-Coast, may as well boot that out too. Just those two devices alone give you two channels of CV/gate, which is plenty; going for four separate signal flows in this small a space is probably a bit of a stretch.
Last thing I'd do here would be to change up the layout a bit. Try and get your audio chain in one row, the control chain in the other. I can pretty much guarantee it'll make the synth easier to use in the long-term.
Thus far, though, the idea's on the right general track. Now try and see if you can mash things even tighter while at the same time reducing the monetary outlay. I think you'll be able to pull that off pretty easy-like!