I got lots of rejects (stale) on Antpool and the performance wasn't so great.  

Having much better luck on Flypool.  Very few rejects and generating ZEC0.153/day over the last few days.  (I'm o/c to 750mhz btw).

With the spike in ZEN value yesterday I flipped back to Zhash.pro for a bit but it underperformed Flypool.  Very frustrating that I *never* get the estimated results Zhash.pro lists on their website -- far below, in fact.  Flypool is much better and more accurate at reflecting estimated results.

Zhash.pro is so bad at its estimates (always on the high side) that I think it's intentional.  Usually estimating ZEN1.3-1.4/day and in actuality I get (on average) about 1.1/day.  Worth doing the math if you are trusting the estimates yourself.