The overall lag is his lag + your lag + server lag. According to the net connection stat the server lag is verry low and most people have a lag below 300ms to the server. Aditional there is some computing time in between.
AH2 covers up some of the lag with prediction but basically 0.2-0.7 seconds of lag remain, so he might get of a shot eaven though on your side it looks like he doesnt.
But since you know how it looks from your side when he is about to hit you do not know that he actually pulls more lead than you see there and think hell hit. So there is not much problem about that. It is a bit more difficult with the collisions, but if you collide with the enemy you flew to close to him anyway, no matter if it was a near miss on your side .