redundancy is often a good thing in modular - but in a small case like this with big modules...

I think the qcd and expander is way too big for this size case - especially as pam's can do 80%, if not more of what they can do - same with the euclidean circles - Pams does euclidean too

and to some extent the same goes for compare2 - in this size case I would concentrate all my trigger/gate generation from Pam's, which has built in logic functions - not as exhaustive as compare2 - but for me that would be a next case module

I would focus more on modulation:
maybe something like maths - it's a fantastic learning tool - especially when combined with the maths illustrated supplement - available online

and utilities:
you can never have enough vcas - use them for everything - modulating modulation, note shaping and volume are only 3 basic uses - want a sidechain compressor - patch it up with a vca, want an auto-panner or a crossfader - vcas...

switches - are they going to do exactly what you want??? exactly as you want it - I have a feeling they won't - some AB switches probably would though - the switched multiple is a great module - especially when you abuse it as a gate/trigger combiner - not advised by many - see Steevio and MylarMelodies though as they both use this technique - as according to Mylar - Steevio once said to him - "I've been doing it for years and not broken anything yet!"

sub mixers - it's really useful to have a few modules scattered around that can create submixes - especially if one is featured like shades - where you also get attenuversion and a precision adder thrown in

if y0u can find kinks buy it - it is a great small and inexpensive utility module that has been discontinued recently

power - I hope you have the turbo boost wall wart and not the regular one - the modules in your rack draw too much power for the regular psu and you are at very nearly 1A on the +ve rail

you should leave at least 20-30% headroom to accommodate for inrush draw on top of what modulargrid says and I add 10mA per hp to each rail for every hp that is not filled to allow for expansion

"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