I'm sorry but your argument seems based on having already pulled the radiator and headers and a ton of other crap.
Let's rephrase. Two bikes in road ready trim. Time with a stopwatch how long to simply get the valve cover off? Because when you say there's a ton of room above the valve cover, that's the opposite of what I've heard. It's really hard to imagine the Kawasaki having the shortest time.
How about this; can you adjust valves?
Have you taken both styles apart?
I am telling you my personal experience with both...I even provided pictures to support my points.
I also already told you the exhaust and radiator had nothing to do with the valve adjustment.
You are free to belive whatever you like.