I received a targeted offer in May for a AMEX Business Platinum--AF waived first year and 100K MR points for 10K spend in 3 months. I decided to go for it and dropped my Personal Platinum card--didn't need to Plats (w/ 2 AFs) and my Personal Plat renewed in June--perfect timing . Before canceling the Personal Plat, I bought 4 Delta $50 eCerts to use the Airline Fee Reimbursement benefit.
Fast forward to last week, decided on returning to the east coast for the Thanksgiving holiday and found a reasonable fair--$299.20. Never used eCerts before on a ticket purchase--had no problems applying 3 of the 4 I purchased to max out the credit allowed and billed the rest to my Business Plat card. To my surprise, AMEX applied an Airline Fee Reimbursement credit to the full amount of my ticket, $149.20... effectively making it free. Didn't expect it, but not going to complain as I would only have purchased more eCerts at the EOY if I had any of remaining $200 Fee Reimbursement to make use of then.