Bump from the past - new real info!
I plugged my 360 into the Xbox One, and set the 360 to boot directly to Media Center.
While I do not really want both consoles on to watch TV, it works so I will live with it for now.
One Guide changes channels correctly for the 360 media center, and a nice bonus is that I can pause live or recorded TV with voice (or X1 contoller). Voice skipping forward and back seems to work fine.
(sorry, holding a twin and feeding him while trying to type, so I will update this more later) I am surprised out how well it seems to be working, I am using smartglass in place of keeping the old controller around.