It is too much like CoD. CoD operates on an instant kill from any angle. Now Titanfall has joined that group.
When you unload round after round on someone as they are running at you, only to get the instant kick to death and see they are living at 10% health.
Executions have an instant kill too. This is a problem because we get to execute and it has an animation, leaving you completely exposed. Where is the incentive to go for the execution, if the kick will do it quicker and leave no risk?
My Proposed Answer:
Give it the BF and Halo treatment. Meaning any angle is two-hit kills. The sneak behind, is an instant-kill execution.