i very quickly learned that for me there is absolutely no time when temp set above 450 is appropriate. you get just as good cross hatch sear lines at 450 and you have a bit more time to make the process manageable. If you don't quite get up to desired internal temp before completely charring the steak then finish it off on the indirect side.
I've become comfortable with the smoke leaking back through the pellet hopper. It was a bit disconcerting at first, but after a hundred hours or so of this happening with no catastrophic results I am now at peace with it.