An unofficial release of a version of the Xposed framework was released yesterday that allows users to take OTAs without restoring a stock image and also allows Android Pay to function (albeit with a reboot required to turn off Xposed).
Unfortunately if Xposed is running in any fashion the device will fail the security checks Google has in to make Android Pay function, but the reboot and disable can be done without a cache rebuild so you’re looking at about a minute to get Android Pay up and working, and another minute to get xposed back and flying.
The OTA ability comes from the Xposed installer not touching the system partition, and your milage may vary from device to device. You’ll also have to use a systemless SuperSU if you’re interested in OTAs.
The current unofficial release only works on Marshmallow and up, and may or may not work on your device.[xda-developers]