First off, seems the overwhelming majority play NLHE. While even 8 tables seems tough to me, it is impossible at stud games (includes razz). You will lose all day if you're not keeping track of other peoples show cards, and what's already been folded. That said, I mostly play Omaha HL. While not as focus intensive as stud, it's far more complex than HE. I can play 3 tables very comfortably, but 2 is optimal for getting any kind of reads plus not getting bored. Most I've played was 5 at once, and it was a mistake, lost at all of them. At 4, I've only had a couple winning session.
Riverrogued, you say "The other advantage is that once you have acted, you don't have to worry about anything else with that table unless it comes back around and you need to act again." and "Say you make a good bet, and a poor player makes a terrible call but sucks out on you."
Well, I wanna make at LEAST a mental note, so I can assess his raise or call the next time. I see what your saying though. If you play very methodically, and can still win less at each table but more overall per hour, I guess the system works.
BTW, my windows don't pop up. The light flashes in the toolbar and I have to search for them. Guess the pro multis choose the pop-up option, but that drives me nuts.