if you already have plans to redeem those 70K, then yeah it might make more sense. It really depends what you want to do with your miles. Most people here tend to try and drive large balances on a single airline program, for long haul premium cabin award redemptions. AS has some outstanding partners w/ excellent premium cabins including EK, QF, and CX. Of course, AA has access to many of those as well. But if you are planning to drive your balance down to zero anyways or are not saving for a specific, big international trip in J/F, then it makes it more sensible to switch to AS. If you tend to use your miles domestically, AS actually has more options than AA because you can access AA inventory, DL inventory (for now...), and AS inventory. Internationally I would say it is a wash in terms of access, but AS has better redemption rates than AA (fewer miles for the same trips in general).