Have you? I've tried on a friend's Mass Effect cosplay armor. As for real stuff, I've worn combat vests and general bulletproof vests that go under casual clothing. The majority of the stuff I've tried is certainly not for the female anatomy, but some of it does and it works wonders. But you know what it doesn't do? Lift and separate my boobs. Because that's stupid. My issue here is that we don't need to lift and separate breasts but we can still compensate for them in armor, but without making concave breastplates. What's so difficult to understand about that?

I fence, and I have female friends that fence, and when they do they wear a plastic chest piece under the fabric that look quite a lot like the female ME chest plates.

That's incredibly stupid and quite frankly, I almost think you're lying. How does that serve any purpose at all? The fact remains that a concave breastplate that points in to your sternum is doing nothing of use in terms of practicality or safety in combat. Nothing. Granted, breasts (male and female) take up space that can be accommodated for without hindering the wearer.

I am not lying, nor am I trying to argue.

Sorry, I'm merely trying to express my disbelief in the idea of someone using such armor in real life. Just... what?