But how do you impress the judges?
There is nothing wrong with using a saw, and a silky or similar pruning saw can produce a really good clean and fast cut, however traditionally hedge layers would cut off the heal with an axe or billhook, not a saw. This is not easy, your axe or billhook needs to be razor sharp and you aim needs to be spot on!
Your judge will be looking for a neat job and will award more marks for axe/billhook work, but it has to be done well!
Good luck, and don't forget to sharpen your axe!