gridiron

I am trying to decide if there is any advantage to purchasing a 4 device Medallion Net plan in advance of our holiday cruise onboard the Island Princess. It does not seem that there is an advantage to pay in advance. Unlike shore excursions, I do not seem to be able to use my OBC to pay for this and would have to use a credit card. I am an elite and still being offered the price of about $15/day 30 days in advance. Am I missing anything? Thanks!