As much as I'm sure a woman likes a nice size cock to make her feel "full", I think this cock size thing is just a bit overplayed. If you have a man with a nice, thick 7"er, and he knows how to use it, you should consider yourself very, very lucky that he's giving it to you.
I'll never deny my woman her desires to fulfill her curiousities or fantasies, so if she wants a black 9"er to do this, then we'll go in that direction. But, in the real world, there's nothing a 9"er is going to do for an average woman that a nice, thick 7"er won't do just as well. My main focus is to see that she's getting sexual satisfied.