From the tone of your post, you sound very pressured. The worst thing to do is making decisions based on feeling pressure. Understand that six months is more than sufficient to follow through on the dispute process. NCO was the first CA to drop off my credit report when I first started my clean-up process in summer of 2007. It was done with one DV letter. That took less than two weeks. The one two punch really works. Should you go that route, within 30 - 45 days you will know which companies you need to settle with. Should it come to the point of having to settle these accounts, only do so with a written statement in hand that they will delete the tradeline with payment.
Just remember to never let them see you sweat. Six months is plenty of time.