I'm new to modular and after some research this is what I've come up with. My goal is something well rounded with lots of different possibilities, but leaning towards ambient, generative soundscapes. I'm thinking about using it mostly by itself and recording stuff into a DAW. My idea for a case is a Intellijel 7u.
However, if you're going with a Rubicon, then I think you might want one more oscillator. The Rub's most notable feature is through-zero FM, which means you want something to FM it with! (Usually that means another VCO generating a sine wave, though you can use other waveforms, and if you have a filter that track 1/v over a good range, and which will self-oscillate, then that could work too).
I'd be tempted to lose the Disting, the 2Hp Compressor and the 2Hp Mix, and replacing them with a Dixie II+ to get that extra oscillator.
(The Disting is great, but it's a pain to use because it does so much with so little UI. The Mix is useful, but you have a Quadratt, and the Comp is a bit redundant when you have the Ghost).
Next up, the uMidi is also redundant - the Expert Sleepers does everything that can do and more. How about ditching the uMIDI and buffered mult (you can use stackable cables, and all your module choices are properly buffered, so you shouldn't need an active mult) and replacing it with a second Quadratt. (I have three of them in my current case, and I use them for just about everything).
I'd also consider swapping the Quad VCA for a Mutable Veils V2; it's another quad VCA, but would save you 2HP and it has a nicer interface (if you like sliders, which I do!). And you could use that spare 2HP to drop the 2hp adsr and replace it with a Frequency Central System X envelope. (The 2hp modules are actually really good, but they are a bit fiddly. IMHO they work better for things you don't tweak to much, like noise. For an ADSR, I'd rather take the System X in 4hp and have bigger knobs!)
Lastly, do you need the input and output 1u modules? Again, the ES can do all of that... Give you more room for something fun?