If ethereum relies on memory bandwidth, how the heck are you guys coming up with these hashing estimates when it only has a 256-bit bus? I don't think it's going to be anywhere near 30mh.
The 380x did 25mhs until the latest dag, now it's doing ~21mh so with the 14nm chips in the 480 should offer a jump in performance and efficiency, especially for claymore's dualminer.