I did a buy on the S4's and their hashrate locally is 2th/s or greater (awesome!) however, when connected to BTCGuild NONE of them show anywhere close to 2 Th/s. They show more like 200 Gh/s. I have 2 that are over 1 Th/s, but the rest between 0 - 278 GH/s. WTF Bitmain?
BTCGuild and Ghash are the only 2 pools which I've tested that actually work. You may need to power down the miner (not a reboot in the miner's web settings) to get it hashing properly. Any changes to the miner's settings without a hard reboot can cause the issue you're experiencing. Very frustrating.