re: Questions about airline (Delta) status matches

There are 4 AMEX Delta cards. 2 types, each with personal and business version. Depending on how much you spend in a year, you can actually "spend your way to diamond" in a year since all of them earn you MQM. But that's an extreme scenario (You need to spend $240k total).

But it could easily be the difference between re-earning gold or bumping up to Platinum with a combination of flying + spending + spg crossover rewards.

Further, AmEx plat comes with sky club access when you're flying Delta. The Delta reserve card comes with skyclub membership meaning you can access it regardless of whether you're flying Delta or flying at all.