Thanks for the input! I will definitely not use the Moog Mother 32 as part of a rack case, I'll use it separately on its own working with the case.
I should've been more clear on what I own.
I own the Prophet Rev2, Op-1, 2 pocket operators, the Moog Mother 32, and the novation mininova.
In terms of types of sounds I want to be able to create, I want to be able to have lots of sources of modulation so that I can create more expressive and flexible sounds. I want to be able to have a live setup that I can modulate on the fly during a performance, and for that to be an easy thing to do in the synth workflow.
-- GavinAnalogSynthsGuy
Expressive, flexible, and easy to use live and on the fly... that's going to be pretty difficult to get from modular. I think you might find that a lot of live playing tries to reduce the complexities where possible. The Plaits and Braids modules, for example, are very popular for live play, because they tend not to need as complex of a set-up having built in quantizing, envelopes, prefabricated sounds, etc.
As Toodee said, there are a lot of utilities that are going to end up in your case to make things work properly. After you're done patching everything up a few times, hunting down problems during a live performance (oops, accidentally knocked that module out of its settings), you'll want to revisit what makes a good live rig versus studio.
$0.02 delivered.