Bitmain hardware is awful. IMHO the last good hardware they made were the S1s. Everything from there has gone downhill.
Again, I have no problem with my s5's. I migrated right from the S1 to S5 on P2Pool.
Maybe it would improve with a change in the software, but my average take and status is well above estimates on any BTC calculator.
I make less on Slush's pool than P2Pool.
Maybe I'm missing something.