mostly looks good
you could drop either the sto or plaits - at least initially, although a simple analog vco and a digital vco are both nice to have
how are you going to play this? sequence from the minibruute?
how are you going to listen to it? via external mixer - NB if you are in an area of the world with unbalanced
I would replace the pico dsp with a fx aid xl - same chip - more options - more modulation inputs
be careful not to overdo it with sound sources and modifiers - I'd try to limit it to 2/3 voices in a case this size
sound sources < sound modifiers < modulation (about 20% of case/number of modules) < utilities (30% of case)
as I think it allows the most variety in patching
so maybe another modulation source would be a good addition - have a play with envelope generators and lfos and coombiiniing them with maths to make more complex modulation - remember to check out the maths illustrated manual - and work your way through it a few times - and keep going back to it every so often - it's a great primer for patching modular synths!
good start all round though!