My comment on your lightening, IMO there is one glaring point where a failure might occur, (EVERY item has a failure point) its on the second LCA pictured, on the top of the LCA (which in use is the bottom), approx 2"? to the left of the pivot point, right above where the adjuster loads against the arm. That area is in tension under load, with the removed flanges in this area. I think this one area is overlightened relative to the rest of the arm, and simply adding back minimum flanges on both sides, or boxing the two sides together would reduce the stress concentration. Is it a big deal, not likely. This mod maybe already in the cards as I have no idea if this a progress pic or completion.

And weights before and after would make for good discussion.