Not too long ago, I had 9 players, too. It was an explosion of colossal scale - I had 3 people leave the group because of schedule conflicts, and 1 person who was so flaky they were never there. I invited 2 new people to join. Then all 3 schedule conflicts cleared up, and it was insane.
4e is very, very hard with 9 players. It CAN be done, if everyone is completely on the ball. But it's nowhere near as slick as the sweet spot of 4-6 characters.
-O
Some might say its just the flaky

