OP is not asking about whether the friend should switch to another loyalty program. The question is simply whether the friend should update his address on his DL SkyMiles account.
Originally Posted by
powerful pete
His question is really about whether there are major differences transferring his Delta Skymiles account from US-based to Peru-based.
No, there should be no major differences aside from eliminating the MQD requirement.
Sometimes Delta does run special promotions targeting flyers who reside in competitive markets (e.g., NY, WA, AK, CA), but that would not be enough reason for me to keep my address in the US -- especially if my address was not in one of those markets to begin with.