"The biggest issue with BAN is that they are hiding where the extra 10% is coming from.
Why do people hide things unless they don't want people to know it."

s0br has let it be known, even back when the amount was 25% that he pays it himself. He has bought BTC to cover what the pool does not cover with found blocks. I was once on the chat with him and he thought he had misplace some coins ( like 2 blocks worth) only to find out a day later when he sent out a pool email that his wallet had been compromised. Even thru trials like that the man has always paid and i have a feeling he is well funded. At the beginning he was doing it all himself and found out it may have been a bigger task than he thought but with so many miners here for the "hobby" and mining at a loss why is it so hard to believe someone wants to build a pool that he can use himself even if it is not a financial positive cash flow at this time?
Disclaimer:  (I really have no knowledge if the pool is profitable or not).