I'd definitely let the ShapeShifter mature in your workflow before adding any new modules.
If you pull the Warps and the TipTop 909 modules, that frees up 18HP.
My first thought was a Worng Vector Space for creating some interesting modulation sources by using what you have onboard. But it's 20HP. So you'd have to find another module to cut out.
A Befaco dual attenuverter would be nice since it can attenuvert as well as offset.
A Clep Diaz or two might be useful for some additional glitchiness.
There's also a lack of effects unless the Disting is being pressed into generating reverbs, delays, etc.
You could also make a go of adding some simple mute switches. Noise Engineering makes a bank of 4 that fits in 4HP. Joranalogue makes a Select 4, which is more involved.
I don't see any logic modules either. A Joranalogue Compare 2 or even something more simple (like a Blue Lantern logic module) might add some tastiness to your patches: AND, OR, NOR, NAND, XOR, etc...
Just some ideas off the top of my head... but it's all going to come down to what makes the experience better for you.