Dont know really, but im getting a better pay out per day vs. middlecoin. So i dont really care.
Its really easy to monitor what coins you have mined, and whats to be exchanged.
And a big plus is that it has vardiff, and they convert all coins before payout, so they dont hold 15% to the next day like middlecoin do.
Try mine there, just even for an hour and then go here
http://wafflepool.com/miners and type in your wallet address, and see the magic.
VARDIFF is nice; if a few folks on here confirm what you say I'll give it a try. For me I'll stick with what works until something is confirmed to be better.