You mean it will go through as a cash advance, not purchase, so that the miles won't go through.
It would seem ridiculous if a major bank themselves wouldn't have the saichel to make it a CA, however, if it works, its worth it.
Not a Wow deal, but something you chap araan along the way.
(Ie, I would setup 50 morgages, just to get this running X 50. ;-). )