I would start at 30% and go up to 50% if you have liquid funds. Contact a consumer licensed in the federal court in Colorado (cough cough) to see if they violated the fdcpa by suing you before validating the debt. If so, a consumer attorney (cough cough) might be able to help you for free :). Good luck.
I am an attorney licensed to practice law in Ohio and some Federal Courts throughout the United States. I am not answering your question to solicit you as a client and there is a good chance that I am not licensed to practice law in the state that you reside. I hope that you find my assistance beneficial and, at most, use my advise as a finger pointing in the right direction. An attorney client relationship is not established by posting back and forth online. One of the most beneficial aspects of working with an attorney is the attorney client privilege which does not exist when you post personal facts online to faceless strangers. Hire an attorney if you want specific legal advise. If you cannot afford one, call your local bar association or search "(your city) legal aid" online. The fact that you took the time to post your question online likely means that you could use the aid of an attorney. Call around your area and see if any local attorneys offer free consultations.
According to your post, you owe the money and have the ability to pay. The honest and honroable thing to do would be to pay your debt.
As for the debt validation request, such a request does not affect the creditor's ability to take the matter to court. This is especially true if you are being sued by the original creditor rather than a collection agency. You're scheme isn't likely to change the negotiations in any appreciable way.
Of course, the truth is that the creditor will take something less than the full payment in order to avoid the cost of pursuing the case futher and the risk of bankruptcy or other contingencies that would interrupt full collection. If you insist on paying less than you owe, contact the creditor and make them an offer. If they don't accept the initial offer, they will likely counter. Work your way to an agreement.
You can reach Harkess & Salter LLC at (303) 531-5380 or info@Harkess-Salter.com. Stephen Harkess is an attorney licensed in the state and federal courts of Colorado. This answer is for general information only and does not create an attorney client relationship between Stephen Harkess or Harkess & Salter LLC and any person. You should schedule a consultation with an attorney to discuss the specifics of your legal issues.
Understand what a DV gets you. (1) the creditor must cease collection until it verifies, (2) FCRA doesn't define what a verification must contain, so usually, you are only going to get the name and address of the creditors, the amount owed. Sometimes they send a statement, but doing so is not required.