I am using sandisk ultra 8gb class 10 cards. I am now on to the fourth card. Things seem to be better when I use the updated version (v2) of win32diskimager. Quite why I do not know.
I have yet to try placing the OS onto the SSD which is run once the sd card has booted. I will report progress here when I have tried it. This might be some time away given lots of other things are going on at present.