It's funny - I switched to hashco.ws for what appeared to be "more service".  The only problem I had with middlecoin was the occasional stall when switching coins - which was the same on hashco.ws (actually it was more frequent).  I found a newer version of cgminer fixed that problem, and switched back because the profit is higher and I feel more comfortable with the presentation of the numbers on middlecoin (immature, unexchanged, and current btc balance) vs. a single number of an "estimated" payout.  You'll like the cows, their profit is about the same, maybe a smidge lower on average.