There has not been any issue. Don't know if that has changed now, since they are being more strict. To be honest, in past years the prices have dropped the most much closer to the travel date, and most of the discounts (Costco, BJ's, Ent, etc) end up yielding the same total. I don't usually use an upgrade coupon because I think they are not guaranteed. If the best discount ends up being this Ent upgrade, though, I will definetly use it and consider the other coupons/discounts in the book as a bonus! Thanks for the heads up; off to check what rate I get.