Then which set would you recommend as a balanced set between "Fun" and "Competitive"? Q701? DT990? I'm still partial to the 598, since I tried on a 558 the other day. The comfort level for my particular head shape with Sennheiser's clamp design is closer to a 9.5 for me than a 7.
Think of MLE's fun factor as a rating as to how immersive a headphone is. Does it transport you into the game? Do you feel as if you're actually there? I believe that's what MLE's trying to convey in his fun factor. Sure positioning and soundstage help, but so does a good amount of bass. Deep sub bass (for many) add to a fun factor in headphones.
I wonder how much CMSS-3D and Dolby Headphone differ. First time I heard CMSS-3D in game, it blew my mind how stuff sounded like it was coming from outside of the headphone. An AI enemy yelled at me from down a hallway. It sounded like I was there, with a voice coming off in the distance, the hallway giving the voice a hollow-sounding effect. (Note that this is just with the Creative Fatal1ty Headset MKII. http://www.amazon.com/Creative-Labs-HS-980-Fatal1ty-Professional/product-reviews/B002BH3JDA ) That drew me in more than deep bass ever could.