"Any aversion to interpersonal comparisons of utility turns out, in practice, to be a claim that maybe it does not matter if they are poor because they would not appreciate the finer things. It is obvious how to judge any such claims." —Brad DeLong (@delong)
The link between "individual welfare" and "utility" is the desideratum that individual welfare respect preferences. That property requires an individual welfare function to be one of the utility functions that can represent the individual's preferences. But choose carefully.
My coauthors and I argue that an appropriate parameter value for the curvature for an inequality aversion utility function based on the views of a representative sample of Americans is 2.5. Within the bounds of actual current policy debate (Overton Window), might as well be Rawls