I made a screenshot on the 1. pool:
http://s1.directupload.net/images/140127/5kuhbr2h.jpg

I was hashing @ 750kh/s and got 400 etok.
It is possible that the one with 9000kh/s got 5000 etok and the one with 4000kh/s got 2500 etok if they were on the pool the whole time.