I've seen videos where players kill others with the taunt kill from a couple meters away , kill others from on top of them, to killing them below them.
Ex 1: Player A = Heavy Player B = Enemy Player
A-->________B
Results in kill.
__B______
| |
| |
A-->_|________|
Results in kill
A-->B
Results in kill.
So what exactly is the range of the heavy's taunt kill?