If running XR500-V2.2.0.7-RC2 do we update to XR500-V2.2.0.4.img or stay on RC2?

Stay on .0.7 - this contains hotfixes for minor bugs. Once it has passed full testing it will be available for general download as .0.8

(note: there's no need to upgrade to this version if you are on 0.4 and everything is working as expected)