Good golly! Now that's what I call nice pictures!!!
Thanks for posting this, I'll be adding the link to the first post! Glad you made mention on a few points I forgot...
My personal reason for choosing 7 and 9 if I were to choose both, was because to me the 9 and 8 overlaps a little; at least in terms of timbre, albeit not completely the same. I liked the definition on the bass the 7's offer (I'd EQ the rest for vocals), and for the sake of having two very different sounds, 7 and 9 came up.
I still think 8 and 9 are the most suitable for the Head-Fi crowd.
Have you tried them with other tips? Like Sony Hybrids or triple-Flange. Was wondering just how much difference in sound it would make.