Armor should affect knockdown. this way people would not build for KD as they are not able to assure the opponent is armored in some way.
Armor would be a little more usefull, and it's also realistic (it's harder to push someone with heavy armor). Two good points for making armor influence this. Furthermore, 30% chance is insane for an instakill thing like knockdown. When it happens, you are 99% sure of killing the knocked down char, so we are better making this as rare as possible.
