I don't know about stealing shares but I tried both unimining and zpool and both were giving me very poor returns compared to the WTM estimates. I was just mining keccak on nicehash instead but it's not profitable anymore. NLpool is the first one that has been giving me anything resembling what WTM estimates.

Edit: I should add that I've only been mining there for about 7-8h though. So far so good.