I updated to N with the Sprint RUU, and it still doesn't contain an rfg_3.img, so I'm still good to run LOS. It'd be interesting to know what the differences are. Maybe it could be implemented in LOS. Then Sprint users would not need to be s-off to make the necessary changes.
What I did was flashed a modified firmware and when I switch back to Sprint's Firmware I was still able to boot that IMG might be in here imma check it out