Either Vltor or Larue will do. Pinned to ensure GB stability.
+1 on the range time and ammo but the hardcase is something nice to have but more of a want than a need IMHO.
You might want to wait a while, shoot, do research and see which optic option would suit you better.
From my personal experience, I like the Eotech's reticle over Aimpoints big dot but prefer Aimpont's battery life meaured in year vs. Eo's measured in hours. I dont care for Eo's 8 or 4 hour auto shut of but like the idea of direct mounting. I prefer Aimpoint's 1/3 vs. Eo's absolute co-witness. Lastly, in my case (owning a 511), prefer Aimpoint's battery choice over Eo's PITA N-type.
Again, at thre risk of sounding redundtant, I have a 511, and after a few rounds down range and a hunting trip or two... if I had the chance for a do over, I'd opt for a Micro T1 instead. I like the size, battery life and type, and co-witness. Again, all up to whatever suits your needs and preferences.
As for your BUIS option, I too am battling with the same options. I like the quick activation of the MBUS, primarily the thought of being able to simply click the front BUIS on with my thumb while shooting, if need, but I presonally feel more confident with Troy's choice of material.
I guess it boils down to a balance you can live with. Ensured durability vs. quicker deployment, to be specific IMHO.
Leaning towards Troy at the moment but not completely shutting off the idea of the new MBUS.