I set my 19' monitor to 1600x1200 resolution. I get 5 tables on mini view with no overlap. I could get even more if I wanted, at that resolution.
5 tables on prima does take a lot of concentration. It's amazing how whenever you finally get a hand..you will also have a hand on 3 other tables.

Right now my PTBB/100 is 8... which is decent..but I'm hoping I can get it to 10. There certainly is a benefit to seeing more hands as my BB/hr is very high.
This all being said... I completely lose it at 3.5-4 hours. I can't see straight after those sessions on 5 tables.
I'm gonna give it a few more days with 5 tables...but I may end up switching back to 4. That one extra table really does strain me. I have no problem with 4.