too many sound sources in too small a rack (I'd say 1 is ideal in this size case - not 4) - not enough utility etc modules to support them adequately
potentially massive overlap with O&C/alan/pams - all can do turing thing type stuff - personally with multiple sound sources I would just go for a Marbles (or clone ALA are doing a full size one) as this will provide up to 3 quantized loopable random pitch sources (and related gates plus a random source for modulation)
to me the mixing solution seems poor... most people seem to want to use plaits and rings (resonate) as stereo sound sources - whilst the only real mixer is the quad vca - which doesn't have enough inputs to handle all the outputs and whilst it could be used for stereo mixing - would limit you to just mixing rings and plaits - and you would have no mixer channels for the mono sources or for sub-mixing - and no vca channels left over for modulation
I'd want more filters and more effects at the least reverb and delay too
I'd probably go for a larger case to accommodate - these changes - for me it would be a tiptop mantis, but that would loose the 1u and the built in functionality (which is to some extent useful, if you want that functionality - but I never have) and even then I'd only be looking to put 2 (or at a push 3 voices) in
"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