Citi actually just closed my old mtvU card last month or so due to lack of use or something. It's basically been stuffed into a drawer for the past few years after I got the Forward card. From experience, Amazon does earn 5pts/$ on both cards, since purchases there code as a bookstore. Payments, however, code as miscellaneous business services, and probably just earns the regular reward, though I haven't bothered trying as I don't think it's worth the attempt.