Looks to me that you are willing to go for two Brute cases 6U, fair enough. I don't know where you live, but I live in Germany and there the Arturia - RackBrute 6U costs about Euro 311 per rack (at the moment unavailable by the way). That's 176 HP for one rack, fair enough, not too bad to start with, you start with two racks of that, so yes, good to go from that point of view :-)
But let's have a closer look, shall we? Going back to one rack Euro 311 and 176 HP total rack space, this rack costs you 311/176 = Euro 1.77 per HP. That's actually a not too bad price. I use those cheap Doepfer cases, they are a bit cheaper but Euro 1.77 per HP is not too bad.
Let's take that Neutron module now of Behringer, that's 80 HP, so if you decide to put that Neutron in this rack, that will cost you 80 HP * Euro 1.77 = Euro 141.60, you have to add that on top of the price you paid for that Neutron. Let's say you got that for a flat Euro 300, then suddenly your Neutron costs 300+141.60 = Euro 441.60, is it that worth?
I mean, I put my Neutron in my rack as well but I keep in the back of my mind that I am willing to remove it at the moment I am going to have a HP space issue; do you?
Better idea might be to keep for the moment that Neutron in it's original case and just start with one rack (instead of two but prepare yourself to spend money for a second case). I believe once you removed the Neutron that most of it will fit in one rack. I usually ask people to keep at least one row free for future modules, so that would be your second rack then :-)
Or yet another idea is, you straight away go for the Doepfer - A-100LMS9 rack, that's a 3 row 168 HP rack, gives you a total of 504 HP. That rack costs here Euro 701 / 504 HP = Euro 1.39 per HP, still (much) cheaper than the two RackBrute 6Us. With this low cost monster case or whatever it's called from Doepfer, you can leave that Neutron in it, space enough for the moment and if you need space prepare yourself to remove that Neutron (or keep it out of the rack directly from the beginning).
These are just some ideas to chew on :-)
Generally I see some modules you could leave in your rack design (Maths, Mutable stuff, the Pamela's) however you might want to consider to reduce (to start with) a bit on the "fancy looking" modules. If you must have a few of them, then just start with one or two of them. Get some experience and then consider to get one or two more, build up again some experience, etcetera.
I do miss classical modules like oscillators, LFOs, simple EGs --> Maths is not that simple and it's a rather big module, so you might want to reconsider that one; on the other hand the entire world has a Maths... up to you :-) Get at least one more filter. I see, if I counted correctly, 3 sequencers but I am missing a bit the classic stuff. So you might want to have a look into a more "equal" distribution of the functions.
I don't know all the modules you have in your rack, so I might have overlooked here and there a function that you actually might have already put in the rack, fair enough. I just provide you here with some food for thought :-)
Good luck with the planning and kind regards, Garfield Modular.