The bottom line is you are hosed no matter what you do as soon as any collection or charge-off gets onto your credit report.
Paying it off does no good, as the FICO scoring system is utterly indifferent to anything GOOD you do for your credit, including paying a charge-off or collection account. And the collection agencies being the crooks they are, half the time they take your money and don't even update your credit report. Expect to spend months if not years chasing them down, mailing copies of canceled checks and whatnot hither, thither and yon, and riding herd on all three credit bureaus. Then wait another three to six months to actually have anything on your credit report change.
And did I mention FICO STILL won't give a hoot?
My advice is to just keep your money and not bother with your credit score. FICO is up there with global warming and international terrorism as another negative of modern life you can't do anything about anyway.