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SvennoJ on 02 December 2013
Saw it on Eurogamer
http://www.eurogamer.net/articles/2013-12-02-every-xbox-one-really-can-be-a-dev-kit
Don't try this at home is the official message for now.
"Changing the settings in this menu is only intended for developers for Xbox One, and this alone does not turn the console into a development kit. We strongly advise consumers against changing these settings as it could result in their Xbox One becoming unusable. Customers who have put their consoles into this developer setting can revert by restoring factory defaults under Settings / System, select Restore Factory Defaults."
