<<So, does anyone know if they're really tracking the $5000 limit? If someone were to *ahem* go on multiple trips over the next few weeks, and they weren't recognised at the store, it seems like there is no procedure in place to stop them from spending more than the $5000, right? >>
My understanding is that Amex keeps track of the $5000 limit. So if you go over, they'll charge you the difference.