I currently have a GTX 960 Strix 2GB, but would like to switch to a 1060 6GB, is it a worthwhile upgrade?
How many sols the 1060 6GB can do?
960 = ~160 Sol/s
1060 = ~300 Sol/s
280-300 Sol/s with undervolting and overclocking.
Hi! You can see the difference with this great tool:
As said above, with a 1060 you would get ~290-300 H/s. Now it’s incredible profitable to mine, and the Return of Investment is less than 3 months for that card. Let’s hope it lasts! 
Have fun!
I bought today a 1060 ZOTAC 6GB. And a riser from aliexpress (one month to arrive zzZZzz) to work along with my 960. I expect something around 450 sols.
In some time I will replace this 960 with another, perhaps, 1060, because of its energy efficiency. I do not want to change PSU (EVGA 430W).
your psu could handle dual 1060 with your current pc specification