The 1060 6gb cannot do 25mhash ethereu.. Stock clocks aound 15-18mhash. With oc 18,20 or 22. Depends on the memory type.
Hynix is slowest, then micron and samsung is the fastest.
How big is the difference between 3Gb and 6GB versions?
Is it worth to buy (say) 6GB for 250 euro, instead of 3Gb for 200e ?