Please check my post if you are interested in Buying Gears Of War 4 which also includes Code for entire Gear Of War series. Additional discount when bought with Xbox Live 12 months Gold card or Console.
Xbox One S (500 GB Halo Collection Bundle) with Xbox Live 12 months card
Xenon model can't be RGH along with the latest revision of Slim (After August-2011 I think) because Microsoft has removed the HANA chip (the core component for RGH to work).
FYI: http://team-xecuter.com/new-xbox360-slim-motherboard-corona-hana-chip-gone-3/
I haven't tried it yet but I think this is what you are looking for. I am having a wonderful time with my RGH console, playing all GOD games. Will be doing mod for two friends in coming week :)...