I'm guessing you were a 2nd row Marek, or maybe number 8. Good point on dislodging the ball but I think you're going to take more of a beating from all the big hits.
I accept that some of it is a size issue. There's no way I could bring down a 6ft 15 stoner from waist high, but take the legs and his own weight and momentum brings him down.
A few in the RWC seem to be favouring the good old fashioned round the neck approach, bet they still wish spear tackling was legal.