Benether, since you are already using claymore miner, did you also try dual mining? And did you play with -dcri values for balancing eth/dual coin
Ofc in case that overclocking core on 970 gives adequate ethash boost, that means that ethash algo uses all gpu power, in that case dual mining will not be of much use
Yes, I currently mine ETC+SIA with claymore.
You can live test "dcri" effect without stop/start mining using "+"/"-" keys ( Cf claymore readme : You can change the intensity in runtime with "+" and "-" keys and check current statistics with "s" key.)
For me, the default value (30) is fine, but i havent tested it a lot.
I've see a very little hashrate drop when dualmining vs simple mining.
I've also noticed that their is a strict 10x ratio between ETH hashrate and Sia ones (if you have 19 MH/s in ETH, you will have 190 MH/s for SIA) and i dont think OC or not change anything (i supposed sia mining is just using what is not used from eth mining, OC will just raise both hashrates)
Let me know if you find some interessing settings for dcri/OC.