a big part of the journey is the research and thought that goes into it, it's your custom synth not mine!!
sayng that - don't overlook doepfer for utilities - they are inexpensive and do the job perfectly well - their a-151 sequential switch is a bargain, for example! but if you're looking at xaoc devices then for utilities samara II is hard to beat - it's definitely on my want list the future!
with regard to mutes - it's often better to mute gates/envelopes that are opening vcas, than muting actual audio - as muting audio can cause unwanted 'clicking' sounds - so maybe carrying on how you are doing it
if you can find a reasonably priced wmd performance mixer, I'd jump on it and see how you get on... you'll probably not lose money if you come to resell it in the future! just remember that you'll probably want more envelopes and modulation sources to drive the vcas and vcpanning - a good idea is to use the built in vcas to control overall volume of the channel - using another vca before to control the shape of the note 1st
"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