eTH uses less?
No it doesn't, this statement is wrong. Mining Eth absolutely uses more power than ZEC with all clocks and voltages the same.
As for dual mining, I concur with the fact that solo mining Eth is more profitable. You actually lose money mining SIA or DCR as the extra electricity cost is more than what you mine.
@Walrusbonzo - yes i agreee with you, i use around 10-15% less power mining ZEC than ETH, it was lower but the newest version of claymore raised power use by around 5% across the board. But even with the higer power use Eth only seems to be alot more profitable than ZEC now
Yes, the newer version of Claymore does use about 5% more power, but also gives around 5% more sols, so it's about even in that regard.
The thing is, when keeping settings the same you can switch from ETH to ZEC and notice about a 10% power drop with no other effort as has already been mentioned, but if you make a custom ZEC WattTool profile you can drop another 10% off this as ZEC will allow you to drop the wattage more than ETH will without crashing. So it is a bit more work, but I modified my launch batch files to run WattTool with GPU initialization files customized to ZEC for lower power and another customized for ETH.