I wonder if armor getting shot off is just a power armor thing or if that extends to all the layered armor as well, and what armor getting shot off means for the player/enemies. It looked like limbs had their own armor ratings. It'd be pretty cool as far as combat goes if, when tasked with fighting heavily armored enemies, you had to look them over quickly for unarmored limbs or look to break a piece off and create a weak point to exploit.

I think it won't necessarily fall off, but be reduced to "functionally ineffectual".

No, I'm http://imgur.com/a/THHoG armor can get shot off, or at least parts of power armor. The chest piece for what look like raider power armor is gone in the second shot.