it wouldn't really make sense at this point to buy a 390/X/970/980, with the 480 out, even if similar price, let alone if its a bit cheaper, if not for efficiency and features for AMD counterpart, or memory for nvidia counterpart.
i could see ppl reluctant to sidegrade if they have them, but an upgrade from lower, the 480 would still be a no brainer.
Don't you know efficiency is irrelevant now? It was only relevant on Hawaii launch