I was planning to get RT-N66U, but then i saw the availability of RT-AC66U, is it a good time to get it now, because it costs about 20% more only. I will still be using wireless-N, but who knows in a year or so I wanna upgrade to AC then i don't need to buy a new router.

My concern is AC is not finalized yet, it would be terribly suck if 4 months later Asus introduce a RT-AC77U or something like that.