Some questions just can't be answered with a simple yes or no.
she even put on Samus' real face just to mess with her. I don't think Samus is as helpless as you'd think, after all she fought a pair of power suit imitations without her own in Brawl, of course she doesn't have pikachu to help out here...
Well, I guess that means it's shape shifting as opposed to "remembering" old bodies the X Parasites have copied since the SA-X didn't properly copy Samus' form, just the Power Suit (early in Fusion when we first see the SA-X and there's a close-up on it's face, you can clearly see it's not human and defiantly not Samus).
I actualy thought the SA-X was a MUCH more competent opponent then the SA-mutant. All the mutant did was jump around and shit. a very easy-to see patern, and quite exploitable. The SA-X however, has every weapon from Super Metroid, and attacks... well, like you would attack.
He hehe... It was fun.
@Prism - I don't know how defiant the suit was, but it wasn't Samus. Definitely not Samus.
Ah, typo puns, good times.