I've heard people talk about IPC, but don't know much about it. The segments won't be in an issue, neither will the mileage. If it's worth a stop, I'll stop

Now, one thing I thought I read somewhere, but can't seem to find it again... does AA allow a 15% "grace" on the mileage? That is, if you go over into the next tier by less than 15%, they don't charge you the extra?