another possibility for the joinery that keeps nagging at me is to place the 8 hips or principal rafters directly on top of the posts and move the beams down a bit(6inches minimum), getting away from the lack of relish at the top of the post...but how would it be assembled? you would be fine till you got to beam number 8 and then what? this is not a bent it is a ring so assembly is an issue
perhaps there is a lap joint for the beams?
-M.