i love my M60 I've been using it for a week now and i have no issues, You won't need the weights in it.
I never understood the need for weights in a mouse... these ones are < 50g... is that really noticable to people? D: I took them out regardless.
My only complaint so far is pretty minor -- if I move quickly left or right, the scroll wheel rattles back and forth a bit. I know that is just because the wheel is just resting on the switch on the right side (attached to the encoder on the left), but it is a bit irritating. Good thing I don't generally have to move that quickly.
As of now, though (only two days in...), I am completely satisfied. It fits my grip quite well (four fingertips only), so I am set