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Alright, here's what I would do based upon your initial guidance of a techno focused drum machine with a mono voice, and my own experience. Above all, you will need to just decide on a couple modules at first and figure out what you are really missing, then go from there. I'm just a dude on the internet, so it's ultimately your decision. These are just some ideas to think about.
First, Three Sisters is not exactly unobtanium, but in my opinion it is overpriced due to scarcity. In its place, I would recommnd the FSS Timbral Sculptor as a multimode filter that includes a wavefolder. It's awesome. Check out DivKid's demo video.
Second, I am not a fan of Maths or Disting. Sold both and never looked back, but they are good for learning purposes. I've never subscribed to Jim's "modular synthesis vs. synthesis with modules" argument regarding Maths. The Moog System 55 and Roland System 700 didn't have Maths... Was that not modular synthesis? Anyway, Quadrax with the QX expander should serve your function generator and logic needs. Add Pam's Pro Workout for all sorts of clocked, random, and quantized waves, and that's a pretty powerful combo. Pam's is the brain that locks everything together. You can get weird swing and off-time gates with the Quadrax/QX combo, but most techno is going to require a pretty tight groove.
I mentioned Vortices in my previous comment. This will give you mono and stereo channels, CV control over mixing (something you were missing in your previous iterations), and clickless muting of channels if you track down the V-Mutes expander. You will want channel muting if you are making techno.
Plaits is so versatile. For a small rack, I think you will find it incredibly valuable. It can serve as a mono synth voice, chord generator, percussion, noise, jack of all trades. Add that to BIA and a good kick drum, and you are in business.
I would ditch the Orion phaser. I think there are better uses of that space, and both Disting and the FX Aid XL have phaser algorithms if you think you'll be doing a lot of phasing (the FSS Timbral Sculptor also does a convincing phaser, btw).
Some of the stuff you chose might be a good purchase once your rack expands beyond 208hp (and, oh yes, it will expand beyond 208hp), like the Compare 2 and compressors. As it is now, you want to get the most out of your rack without sacrificing playability. All of those little 2hp and 4hp modules that you are trying to squeeze in will be a source of frustration. You won't be able to get your hands in between the mess of cables.
Finally, you still have 14hp to play with and I saved you $1100.

Have fun and good luck!
-- farkas

Excellent advice in general from @farkas once again...

I'd upgrade the fx aid xl to a pro... I have both and the ability to actualy see what you are doing on the pro (instead of having to memorise which algo is where or refer to a paper or pdf cheat sheet constantly) is priceless... I'm going to set mine up so that the 1st 32 algos in my pro are the same as the 32 algos in my xl, so I have an in rack cheat sheet... plus it has a very, very basic single channel scope built in