Two convincing wins over Australia have got the three-times world champions back to winning ways after they lost a four-match series against South Africa 3-1.
The Springboks have ridden a physical, conservative playing style to back-to-back World Cup triumphs but Rennie said he remained convinced the tactics that put a premium on ball speed and width would be effective against it.
"There's no point playing this way and then going to a World Cup and trying to play risk-free footy," he told reporters after the 42-21 victory at Stadium Australia.
"We're well aware you can put yourself under pressure the way that we're trying to play, but we'll also back ourselves that we'll profit more than we'll suffer in those situations.
"I don't think you want all the teams in the world playing the same game. I think if you look at the Wallabies, they're pretty similar to us. I think they'll want to play, and it's a point of difference, part of the DNA of both sides."
"If you want to just get into arm wrestles with a couple of the big sides in the world, it'll be a struggle," he said.
Despite his team scoring six tries with some breathtaking rugby in the first half on Saturday, Rennie said there were still improvements to be made.
"We're trying to grow our game, and we've got a long way to go," he said.
"We just want to be able to play at a tempo that will test other sides."
Australia coach Les Kiss said he was pleased with the performance of flyhalf Declan Meredith in only his fourth test and remained confident the Wallabies could put on a good showing at their home World Cup next year.
"I've always said we'll have ups and downs, and today it was a bit of a downer again," he said.
"But there are some good clues about what we're trying to do in our game. When we do play with footy in the hand with a positive intent, we're making a lot of breaks against one of the best teams in the world.
"So I think there are some good qualities that are coming through. So I'm optimistic still."