I suspect that's what mesadler was referring to. R.P. tends to know what he's talking about in the miles department.

That may get you an AA flight, but it doesn't get you AA miles if you want them for something else. You might be able to talk AmEx into buying miles for your account. They may be able to get a better deal on miles than we can individually, though I don't know if they'd admit it, and of course we can't buy them with MR points at all individually, but it might be better (in terms of how much you lose) than other laundering options like Hilton.

Diners is pretty flexible in tailoring rewards for just about anything you want. I don't know about AmEx, but they could do this in principle and they ought to be at least a bit flexible at the higher membership levels.