Ok cool, just wanted to make sure. The knifes not doing damage from the ground thing is interesting, but isn't that very similar to your bomb idea? In both cases you're running a risk by attracting, although I guess the bomb is a more consistent and direct way of preventing just holding the attract button.
Personally, my own strategy is I take a knife, and then constantly reuse that knife to kill everyone else. I only repel and attract when absolutely necessary.
I'm actually trying to play while holding attract constantly, and I'm finding it very difficult. I'm not sure what your secret is, but clearly you mastered my game! Time for me to master yours :)