Long time lurker. Just wanted to let everyone know that you can get the bonus on this card multiple times (surely some of you must have worked it out, all though maybe people don't want to draw attention to it?). I have an Edge, and my Explorer came linked back in October last year. I de-linked to get the bonus points, then re-linked. Then, de-linked again in November and thought I'd have a crack to see if bonus points posted again with $1500 spend. Sure enough, 100,000 points came through.
I've linked / de-linked 3 times since. I'm now up to 500k bonus points, and will likely stop here
Of course, there's always a chance that AMEX will work out what I'm doing and close the loophole (though none of the CSRs have questioned me when I call up with my link/delink request as yet) - hence my rule has been to transfer my bonus points out to SPG as soon as they hit my account.