The 2GB cards should still be able to mine Exp and Ubq. 
The only reason they can not mine Eth is because the Dag file is larger than 2 Gb.
The question is how much juice do they draw.... Some of the older cards use a lot of Electric and will cut into any profits you are trying to get out of them.

As for your 6x1070's there are WAY more profitable coins to mine on them than Eth.