Looks good. To follow up with some of the other comments:
Two ADSRs would be nice.
You might also want to squeeze in a dedicated LFO module that can be restarted/synced.
I'm not familiar with your ADSR/VCA combo. As long as the two circuits can be used independently, that's fine. Else I'd want them separated, even though plugging an ADSR into a VCA is pretty usual.
The Disting will give you a lot of different features to play with. You can then figure out if you'd like dedicated versions of those programs.
With all of the inexpensive case options that are about to hit the market, I'd definitely go bigger unless you really will not expand the system in future.