The FICO formula is utterly indifferent to whether or not a chargeoff is paid or not. The FICO system is designed to only log negative data about an account and to ignore any positive data that comes in afterwards. Once it charges off, that's the end of the story...you get a big fat ding and there's nothing you can do about it.
The only advantage to having a charge-off listed as "paid" is that, for loans where a human actually has input on approving or rejecting you (many mortgages and some auto loans) having it listed as "paid" might work slightly in your favor.
But my advice is to not pay anything more on the charge-offs. To FICO, it's water over the dam, and the system cares only about rubbing your nose in it for the next 7 to 10 years, regardless of any efforts you undertake to rectify the defaults.
My bottom-line advice (and it may not win me any popularity points, but you'll see from my other posts I tell the unvarnished truth) is to try and apply for a credit card or two. Not to use for credit, mind you, but simply to see if you have any chance of credit score recovery. If you get rejected, then your FICO is beyond repair, and you're best off to just not worry about it until the charge-offs drop off your account sometime during the next decade. If you really want to buy a house, look overseas where they don't care about FICO.
If you can get an unsecured credit card, then you may have a chance to raise your FICO. Keep the card, and charge just enough to get a bill (usually around $20). Give it about nine months, keeping just enough of a balance to have a bill, and see if your FICO goes up. If it does, you may be able to recover. Try going for a credit-line increase. If it doesn't, or you get rejected for a credit-line increase, just forget about FICO; it's no use trying to raise it.