The more rules there are for a given subject, the more it feels like the game is emphasizing it, and the more DMs will use it. Look at D&D, with its pages and pages of combat rules, light social guidance, and combat heavy standard of play.

Now, I get what you're trying to do, but I think you could cut back a bit.
  • Under and over- layers, for instance, seem highly redundant from a gameplay perspective-- not just one verses the other, but with armor in general. Five different pieces of armor is plenty customizable; you don't need 15.
  • DR and ER makes sense to separate, I suppose (you could also have the distinction work mostly on the weapon side of things), but having them work in subtly different ways feels like needless complexity.
  • Plate vs Barrier points feels roughly like normal vs temporary hit points, which is fine. You could certainly simplify more, but I don't know that the loss of "feel" is really worth it. Except that having two different kinds of soak (DR vs shields) feels redundant to my inner game designer.

Overall, I suggest cutting back to five pieces, each with their own DR and ER, Plate Points and a "mod slot" (call it whatever you like), which could contain things like underarmor (+DR and weight), barrier generators, coolant systems, weight distribution straps, that sort of thing. That should give you a lot of customization without quite the overload here.