2.5 I guess !?
Grenades are special. I am very rarely hit by them. Kill from afar, don't let them come into rolling range. That's the tactic to protect.
In 2.6 a single hit from a basic hovernet kills my experienced, crouching, armored, full-health, smoke-covered soldier (by bleeding without having a chance to heal). And most importantly, the shot was not even directed at her. Wtf. So the only thing that's no instakill are spiders then. Ridiculous. I guess it's because the difficulty influences damage now.
This basically depends on chance only, cannot be defended against with tactical means, and armor completely misses its basic use. Its use is a weight object which helps to increase carrying capacity.