re: the case dilemma - I'd buy a second mantis - then you have space for all the modules that you already have and for the utilities that you need: more vcas especially - and then the 258t and blades may turn out to be a really useful second voice... (selling the verbos CO should easily fund both a used mantis and veils for example) if you arrange the modules well for your workflow then there'll be no need to swap things around and you can have a performance case and a studio only case - work out how to arrange them and it'll be easy to just pulll out the performance case whenever you want it (don't use the brackets though - otherwise you'll never move them!)
"some of the best base-level info to remember can be found in Jim's sigfile" @Lugia
Utility modules are the dull polish that makes the shiny modules actually shine!!!
sound sources < sound modifiers < modulation sources < utilities