Hi there.
If you're going with the Intellijel 104HP 7U case, it has 1/4" inputs and outputs on the case already. You won't need to add the 1U jack interface that's to the left of the volume control module. The TipTop Z4000 ADSR has CV inputs that can control each stage of the envelope. The Doepfer saves space but you're going to get sick of those jumpers in a heartbeat. The Z4000 is 8HP, so two of them equates to 16HP. The Intellijel dual ADSR is 14HP. I would substitute one of the Intellijel VCA modules for something else that's a little slimmer like the Zlob 6 channel VCA. It's slimmer and gives you six VCAs instead of four. They aren't as flexible as the Intellijel, but you've got that covered with the first Intellijel VCA.
If you can spare even more room, get rid of the uScale and replace it with a micro Ornaments and Crime. It has a quantizer built in, plus a bunch of other features when you're not needing a quantizer.
That Pan Mix by Happy Nerding is an awesome find! I was seriously considering the Roland 6 channel mixer because of the panning... but it also has mutes. But the CV control of panning and volume makes the Pan Mix a bit more attractive. Thanks so much for posting it. You've helped ME out. :)