From Johnsonville almost everyone I've ever seen would use the old Newlands cards - my guess this type of payment was well accepted on these services so Snapper will be welcome here.
The main advantage of Snapper will be time to board - sometimes the green Newlands buses would spend some time on a stop while the driver would manually reload a passenger's card (sometimes more than one passenger).
Some passengers would put their wallets on the readers, the reader would fail (due to multiple cards), then try again but just flipping the wallet to its other side, then when it failed then fumble for the card. The worst thing is that these same passengers would do it again the next day.
I like how I can reload my Snapper card using my smartphone, at any time. No more having to plan ahead to find an ATM to get some cash for the next trip.