if you plot a moving average against that data there are some small hash rate miners around 200th on the list getting better rejection averages than in the top 50. its dynamic and mueslos
graph shows what going on nicely.
The lowest hash rate miners has some total irrelevant data shown that are distorted by quantisation. Please, to see how 512 and 16 difficulty is different for small miners, start a small cpu/cuda miner with 10KH/s, mine for a day at middlecoin with 512 difficulty, and the second day at pool2.us.multipool.us with 16 difficulty. First day you will see 99% lines with "stratum detected new block", 0,5-0,75% lines with "yay" and 0,25-0,5% with "booo". Second day will be different story.
Please note that my post is not in a way of flaming or making someone's hard work look worse, but in a way of making things better, if possible, because I like the middlecoin idea.