Rulers are a very compact boot and will have no problems in any of these bindings (in their largest sizes).
The Boss gets a different toe strap and the Yes I Cant system. If cant adjustability is a big issue for you then you want the Boss. Both are incredible.
I just went side to side and compared the mob boss to the 390 boss, basically the same thing like 1-2 things the 390 boss has more. I just like the mob boss because the color . What you think?