Whether you get hit or not is not determined by the knowledge about the weapon. You try to evade as good as you can, always, against any weapon with the same effort. That goes especially for trained soldiers in deadly danger where a critical hit might not kill but disable you (which could be worse, what are these aliens doing to prisoners?).
"Come on, it is not that deadly, let's take one or two hits, it's not worth moving my lazy a**!" is a sentence you will never hear, think, whatever.
If you get hit the result is the same, no matter what's stored in your brain. Would be a weird experience for a newbe to see that the crazy alien weapon isn't that effective once you use it yourself.
I could agree to some "tactical" difference (type of cover you seek, ballistic curves etc.) but that would better be addressed by different hit probabilities.
I fully support BTAxis and Eleazar in this (if you mind to ask me
).