"The plaintiffs in these cases contend that the calculation methodology employed ... results in inappropriately low benefit payments, typically because mortality tables used in the calculation are alleged to be outdated.... In the first two decisions on motions to dismiss these lawsuits, federal district courts for the District of Minnesota and the Northern District of Texas have concluded that two different sets of claims are sufficient to survive past the pleadings stage. These rulings all but guarantee that more similar complaints will be filed."