Waste of time to reinforce the arms, unless you have some special application none of us here deal with. There is percentage wise so much more "Flex/give" in the suspension design, bushings etc that any reinforcement stiffness would never be even detectable, if even measurable, and the fact that the items never(?) fail, and when they do, in a contact situation, they sacrifice themselves for the sake of the unibody. My money however is on you at least adding the LCA plates, simply because everybody else does, but they also can't share a justifiable reason why, bang for buck, in that if it's just to be stronger, why not use 1/4" plate or thicker?