SandGod,
The 450CRF, has a single overhead camshaft, acting directly on the intake valves (exhaust valves are pushrod actuated). Hond says it has less momentum...why not?
I don't know about the 400EX, bu sounds to me the Raptor has dual camshaft...

 

Heath Voss ran the new 450F very well. Voss is a very fast privateer, and I believe that he has only ridden the 450F a couple of times. It seems like he got 5th in the main. Against Carmichael, McGrath, LaRocco, Windham, Lusk, Ferry, and all those other super fast riders, 5th place is an amazing finish. I can only see good things to come in the future with Honda and this bike. Hopefully, the rumors about Carmichael and Honda talking is true. Personally, I think that this would make Honda an unbeatable team. We'll see.