Lots of audio...but very little in the way of control or modulation. That's a huge stumbling block, as you NEED the control and mod modules in order to get the audio stuff to do what you want. If I were you, I'd go back and delete this, then majorly rethink the bottom row so that you finally do have the right mod/control complement.
Another point, also...the Z8000 and the Pitt Double Helix are hella huge. Taken together, they occupy 56 hp of the total 208, which is close to 1/4th of the entire build. I noticed that you don't have a problem with a second Mantis...which is good, because if you insist on using these, you're going to NEED that second cab. It's not just that they take up 56 hp, either...you also have to factor in ancillary modules for these. The Z8000, for example, has no quantizer onboard...so there's an extra module. Then you'll want some way to make the clocking more elaborate, which lets the Z8000 really get into complex behavior, especially with some Boolean logic onhand. So...yet more modules. Etc.
Instead of the "Buy another Mantis" option here, try and come up with ways to replicate the behavior you want in the build...but smaller, and with more onboard features. For example, the Squarp Hermod is only two hp smaller than the Z8000...but at the same time, the Hermod has EIGHT channels, MIDI interfacing, quantizing, and so on, which eliminates the space requirement for those ancillary modules.
One other point, also...don't assume that you're going to build a separate effects build, because you'll invariably find that you'll want the use of some of the "main" build's modules. It would make more sense to build up a single, unitized system that contains all of these features and then you can have numerous interrelated patches running FX and sound generation, sometimes even in sync with each other.