Not a bad set of choices for an expander cab. One thing I'd suggest for your open space would be another complex function/envelope generator such as the Intellijel Quadra + Quadra Expander mkii, Sputnik Quad Function and Trigger Generator, or the Doepfer A-143-1 (if you can fit a 50mm depth in your case). Since the Shared System will have a Maths, having a different strategy to create complex envelope/modulation curves might be an asset. Also, if we're talking about the original Shared System, you might consider updating to the Rene mkii, as it works together with the Tempi module to unlock a bunch of cross-communicated features. Keep the original, though, as having extra sequencers should never be a problem.