I just noticed that these photos someone posted earlier actually show the design change made to the chest piece/shoulder pad (top photo is the prototype, bottom photo the latest version).
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That said, I'm still not sure the arm is separate from the underlying suit material. I think they may have just extended the chest piece over the shoulder to hide the underlying material, which on the prototype looks to have a some cloth in that area (see below).
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Thanks for the comparison. It looks like an improvement overall, but I agree the verdict is still out on the separate arms. I?m optimistic though since they did this on AM and these were developed around the same time. It?s possible it?s cloth underneath that has the other chest piece over the top.