I've heard of people not getting on with the doepfer midi module before - so I would swap that out - but I've no idea what for as I don't use midi to control my modular
if you need a dual adsr module there are much smaller, possibly cheaper, ones available - frequency central do a dual adsr in 8hp for example - or upgrade to stages - most people don't use full adsr in modular anyway - and get 2 * asr, or 2 * ad and some more functionality (that you don't have and could use such as sample and hold) - or one six stage envelope, for that matter - you only have a single vco and a drum
I'd rather have a filter and use the vca as output - yeah it'll probably be mono, but so what - fine for now!
I'd probably also want an fx unit of some sort - I like the fx aid xl - lots of options and a decent amount of modulation inputs
I'd next be looking to add some utilities - links, kinks and shades are all incredibly useful for not so much money/space - and make a great utility starter set
"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