Samsung Pay as well, at least until someone finds a workaround.
Samsung Pay is a pretty great mobile payment system to have, as it can be used anywhere cards with magnetic strips are accepted, which is millions of locations worldwide, unlike Apple Pay, for instance, which requires that merchants install dedicated equipment. Using it is pretty straightforward, while the service is ready for a prime time and an immediate launch in the US.
If you have a rooted device, though, the following message will be displayed when you try to use Samsung Pay: "locked due to unauthorized modification." Bummer.
It's not yet clear if unrooting the device will bring back the ability to pay with your Galaxy S6 or S6 edge, but this should become clear soon enough. Still, the fact that there are one-click solutions now which can root the handsets without tripping the KNOX counter, bodes well for the future of Samsung Pay on rooted devices.