LD;DR - It's pretty good here, but could be better.

So I've been trying to compare CM with MC, and so far this is what I've found:

-Rejects are high here, that's for sure.  Why?  Well, maybe it's the fast coin switch, or the latency, or the quick growth of the pool, or something to do with the code, not really sure.  You'd think that fast coins should give stales, and not rejects, but I'm sure eventually we'll have more of a concrete answer on this.  As an example, I've been averaging 15-20% rejects here, whereas I've normally had <0.5% rejects.

-Hash-rate seems MUCH lower here, and very inconsistent -- Normally one would expect to take their own hash rate, multiply it by the profit per MH per day number, and get your result.  But with such high rejects, hash-rates are gimped.  A few things to say about that though; it's amazing that the pool is so profitable even considering the high rejects and if we can get those rejects down we're all going to be mega-super-rich!

-An unfortunate side-effect of the unstable / unpredictable hash-rates and abnormally high rejects create a bit of a distrustful environment, at least imho.  This is probably just a lack of education on what's happening, and why it's happening specifically here and not on other pools, so far as I've heard anyways.

-Even with the rejects and inconsistent hash-rate, the profits here seem to be good.  Although my tests weren't the best due to some slight differences in the rigs I used, I've found that at least over the past few days, CM has given significantly better returns than MC.  If you add in the bit of extra transparency, and the 1.x% less fees vs MC, over-all I'm happy to put my hashes here for now.

I was on Middlecoin for a few months, and had some amazing days (ie 0.118 BTC for a single day in Dec with ~3.2 MH), but the lack of transparency, and the recent meh returns has me thinking that this or any other decent profitability pool could have done pretty close to the same given market circumstances at the time.