Hmmmm..to me whether they work or not seems irrelevant.

Let me throw out a hypothetical.

Car A comes with a plastic but adjustable cam timing gear.

Rules say:

a. You can change plastic cam timing gears to metal.

b. Except that you can't use adjustable gears unless fitted as stock.

Does this mean the guy with the adjustable cam timing gear LOSES this "stock advantage" if he switches to metal?

I would say no, and I think the same is true with the RR shocks.