I don't adjust bankroll.
I can't remember any differences from four-tabling to nine-tabling when I made the jump. I did it because I could finally fit that many tables.
You get about the same reads you get four-tabling. You know who the total freakin' morons are, and I use HUD for the rest.
Anyway, the biggest difference I notice is that now when I four-tabling, it's SLOOOOOOOOW.