My 3 Days with 2 S4's
Both of my S4's are running stock settings and always read ~2TH/s on the miner. The poolside hashrate is very different though.
24 Hour on Eligius: ~100GH/s
24 Hours on Eclipse: 1600-1700GH/s
24 Hours on BTC Guild: ~2TH/s (after manually setting the diff to 2048)
The problem seems to be that the pool and miner are not resolving the dynamic difficulty properly. Eligius stick to 128 and results in sh*t for hashrate. Both Eclipse and BTC Guild settle on 1.8k for the difficulty and yield 1.6-1.7TH/s. If you manually select 2048 from the difficulty menu on BTC Guild I get 2TH/s poolside.
NO ONE IS STEALING YOUR HASHRATE. The firmware obviously needs some work in order to properly resolve the variable diff. In the meantime i'm obv mining on BTC Guild with 2048 Diff manually selected.
I'm not looking for a solution, or troubleshooting help from anyone as i've alread done the necessary troubleshooting. (ie factory reset, cable swaps, settings, blah blah) I'm just presenting data of my experience with 2 S4 miners and confirming there is a problem. I can provide screenshots, but don't really think I need to waste my time with that.
TLDR;
Mine on BTC Guild and manually set the difficulty to 2048 until the new firmware is released.