I guess i was talking about the user experience of one store over the other rather than the content policies of either store. Im happy there is more than one option for add ons

For the end user is there really much difference between the two? Click a couple of buttons and the extension is yours. The store is almost immaterial

Seems like a fair bet but i feel like it fits far more with Valves ethos than Microsofts. "native" 3rd paty Xbox could be very interesting though