4 tables of 5/10 or 6 tables of 3/6?

I've been playing 5-10 6max for a while on party, and am beating it for about 1 BB/100 after 60k hands (I 4 table on my Samsung 20" monitor). Today, my friend wanted to see how many tables I could play, so I opened up 6 1/2 tables, and was cracking up at how easy the money was, even after opening 6 tables and not being able to follow absolutely every action.

I haven't played 3/6 at party for a while, and was wondering which is more + EV:
4 tables of 5/10
6 tables of 3/6.

Also, I'd probably get more rakeback, but also be paying more rake.

Thanks,
calcbandit