Moving from 4 tables to 8 tables - please advise

[Pawtucket Pat]

First off, I'm really hoping this doesn't qualify as a zoo post, but if so, bitch me out and I'll repost there.

I've been 4-tabling 2/4 and 3/6 for quite a while with the usual 2+2 2001fp pt/gt setup, and have been doing fine. I'm bankrolled for 5/10, except I'm cashing out a fair amount of winnings and don't want to interrupt the current steady cash flow that would happen with a big downswing. I'm 23 with my first job out of college, so the ability to double my paycheck through poker is very helpful. My long-run goal is to be beating 15/30, but I'm well aware that I a) need to build my roll, and b) need work on my game. However, in the short-run (next 6 to 12 months) I need to make some real cash so I can afford a solid down payment on a condo and stop throwing money away renting.

So I'm thinking of moving up to 8 tables and staying at 2/4 and 3/6 and have a few questions. How much would you guess your hourly rate and bb/100 changed? Is 8-tables a huge adjustment from 4? I know that bb/100 will probably fall somewhat, but that should be more than compensated for the greater # of hands played.

Any advice on this is greatly appreciated. Thanks fellas.