Just wanted to let you know I decided to go ahead and pull the trigger on the entire system as configured in the link (or hopefully pictured if the top picture has updated for you).
I have a 19" rack tower (about 2 meters tall) and have decided to build into that rather than a RackBrute. Lost some space, but building into a rack that can accommodate 13 rows of Eurorack on one side will be years of joy.
I'm a little impulsive, so I wound up going for the Pittsburgh Modular Outs because I couldn't find anywhere in the US that even had the Isolator listed. I'll pick that up whenever it finally comes around.
I dropped down to 3 2hp mixers because I wouldn't have sufficient power connectors. I also got mixed reports on whether or not a buffered mult would be necessary (some people agreed with you, some people said they had problems with splitting), so I went ahead and got two in addition to a passive mult. If the passive mult or stackable cables wind up working for pitch CV purposes, I'll probably swap out the 2nd buffered mult with another 2hp mix.
I totally went for the A-106-1 filter and will have the 2hp comb filter right next to it =D
I also decided I would bypass the MIDI interface and just got a second SQ-1. I also swapped out the Make Noise Function for a Batumi.
So thank you for your advice. It was absolutely influential on my final system and will continue to influence my decisions in the future.