Any time you are sued you have two options: fight or settle. The choice between the two comes down to a question of what is called 'risk-tolerance.' Highly risk-tolerant people are those with little to lose (either in terms of assets, or in terms of liklihood of success in court), or those who, for personal reasons, tend to be willing to risk more for a greater reward. Less risk-tolerant people are those who have assests that would be exposed to a judgement, those who would be personally damaged by being named in a lawsuit, and those who for convenience sake want to end a lawsuit quickly.
The more risk-tolerant you are, the more likely you are to decide that it is in your best interests to fight the case in court. The option of settlement is most appropriate for less risk-tolerant people -- for example, those who are not in a position to deny that they downloaded/uploaded the content that the plaintiffs allege, or who (for whatever reason) are not prepared to be named and defend the case in court.
If you decide to settle the case, the general rule is that the plaintiffs will accept less money the earlier in the process you offer it. Also, if you decide to settle early, you can inclue a provision in that agreement saying that if your personally identifying information ever happens to be disclosed to them, that the plaintiffs will keep that information private.
There are two major reasons to have an attorney facilitate a settlement, if that is what you want to pursue. First, an attorney can evaluate your case, discuss whether settlement is the right option for you, and if it is, decide whether the initial demand described here is appropriate. If the initial demand is inappropriate, an attorney can negotiate with the plaintiffs and try to get them to settle for less than the amount they demanded initially. Second, an attorney can facilitate the settlement in a way that your private information is never revealed to the plaintiffs (for example, by signing the paperwork on your behalf).
Every case must be handled according to its own facts, but the decision regarding how to proceed with the case is always in the hands of the person who is being sued.