I just got the SPG Amex, and my plan is to accrue as many SPG points as possible before the programs merge. Who knows what Marriott will ultimately come up with when they combine the programs. But right now SPG points are the best convertible currency out there, and it's a reasonably safe bet that we will have plenty of advance warning before Marriott makes any major changes that affect the ability to convert them to airline points. Also, the (US) SPG Amex is arguably the best card out there for everyday spend, with 1 SPG point per dollar spent. I really see no reason not to accrue SPG points in the near term.