Word of advice: australians love and trust paypal. (ecom perception)
I thought that there was issues with early stage apps using PayPal which is why the likes of Stripe popped up. Especially around reoccurring payments. I may be wrong.
It might be a disadvantage for the merchant to use PayPal but the customers in Australia on a whole may prefer PayPal to other payment solutions online. The perception that it is safe or what not. If the customers don't perceive your service as a safe option they probably will not buy your product.