Yes. I still get KO'd by sniper headshots, and I've been knocked down at least once. It's only aggrevated becauese I've died as a direct result multiple times.
Probably 95% is max, may be it simply gives formula EN/10% to avoid knock down, but max is 95%, so this 1 knock down is these 5%.
KO is ok, because it's only 50% with 10 EN, so they will happen, but x2 times less often.