We don't normally patch the OS because FPP is not meant to be used in an unsecure environment, so we don't apply OS package updates except when we build new SD images. The aim is to have FPP treated like an appliance where most people don't touch the OS unless they are a real power user. FPP isn't guaranteed to continue working if you are applying your own package updates. It definitely isn't guaranteed to work if you run a rpi-update on it since the FPP v1.8 SD image is based on Raspbian Wheezy, but we are using a Raspbian Jessie kernel and firmware to support the newer model Pi's. The next set of SD images we build for FPP v2.0 will be based on Raspbian Jessie.