"[T]he key to a prudent process for selecting the insured guarantee of retirement income is to compare the competing products in terms of their design, features and prices. This article focuses on the selection of guarantee withdrawal benefits [GWBs].... It's important to look at the financial strength of the insurance company, since the participant's income is guaranteed well into the future. However, it's also important to look at the features of a GWB, as compared to the competing guaranteed withdrawal benefit products."