Hey Jim,
what utility modules.. would you recommend.
I like mixers (particularly matrix mixers and sub mixers with offset and possibly inversion), logic and sequential switches - there are many many examples of all of these available - some modules that you might want to look at adding - wmd/ssf toolbox, mutable kinks & links, happy nerding 3*mia, doepfer matrix mixer & sequential switch
how are 4 voice to many..? would you 1/2 it..?
yes I would only really have about one voice per row, because there's not enough space left over for the modules that are really needed to support them - it's not the number of voices, per se, it's the size of the case... admittedly when some of that is 'percussion' then it may change slightly, as there isn't necessarily the need for filters and other effects for each 'voice', but there is then need for more fully featured sub-mixing, with panning and send/return and effects/filters to use with the send/return
again - look at my signature - the formula there is aimed at getting the most versatility from the least expenditure... it scales well from small systems to much larger systems - as the larger you get the more you want/need different layers of control
"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