He went up the Mary Greene glacier to the NE Ridge, the true summit, then traversed to the West Summit, then headed onward to the SW Summit.
Other than the Main->West Summits traverse (which we did in opposite directions) we were on different routes entirely.
As far as I can tell, our route was a new one all the way from Dark Peak to the West Summit of Bonanza.
I'm still trying to figure out how the whole "climb grade" system works as well, but it would be a grade V if the start of the route is the base of the Dark Glacier (where we roped up from and began climbing in my opinion) and a grade IV if you consider the route beginning at Dark Peak summit.