Null tackles or 2/3 agains should replace 6 agains. I've always thought an entire set is a ridiculous punishment for sometimes just tapping someone on the head. If someone lies down in the ruck for 10 seconds, the six again should be maintained, but for minor infringements there has to be something else.
The other benefit here is that refs are able to blow more "null tackles" due to the low impact it has, so aren't as scared to call one against the home side. Should produce better accountability.
