Excellent, Haven now works perfectly, getting a glitch with Turtlecoin though, says it cannot find TRTL at any exchanges, but its listed at Tradeogre. Here's my config.json for it.

{CoinFullName: "Turtlecoin", CoinShortName: "TRTL", Algo: "CryptoNight-Lite", BlockReward: 29428.03 , BlockTime: 30, BlockExplorer: "https://trtl.semipool.com/api/network/stats"}

For what's it worth, I totally agree.

It might have been profitable to dual mine in the past, and possibly still so if you happen to have free power, but I calculated I used about 35% more power.
Worse still, stability dropped, and you pull more power out of your PSUs, which probably pushes them away from optimum efficiency.

Furthermore, solo ETH, I can run 6x RX580 off a single 1000W PSU, and have it sitting at 91% efficiency, (down from 93%). (Costs me 2% loss over time, verses cost of another PSU. Long term, that 2% is going to add up, and 2% would surpass cost of another PSU, so it matters).

Dual mining, I could only run 4x RX580 stable. (I could start claymore with gser 2, with 5x RX580, but had a LOT of interruptions, crashes, freezes etc).

Conclusion: Factoring in 35% additional power consumption costs, plus a 33% increase in the number of PSUs I needed, (plus their losses, (7%) plus further drop in efficiency), it's very hard to see where you'd expect the payback to offset these added costs.

Then, as Jackbox astutely pointed out, you have to factor in the added stress, and reduction in MTBF.

Assuming you're located at higher/lower latitudes, through the winter, assuming you can swap out air, you save costs on cooling. Come summer, you're paying more for cooling. Dual mining was astounding how much hotter the GPUs ran, (last winter), come summer, your fans are working harder to cool.

More costs.

Cool and steady = stable = consistent revenue.

The added down time I hit dual mining, (a considerable loss in itself), was the knife in the back afaic  

It was worth the experimentation, conclusion was clear.
Far more good reasons NOT TO dual mine, and no good reasons for it.
At least in my experience.

Footnote: I made NO extra profit dual mining, even if I ignore the cost instability cost my ETH mining, comparing ONLY the additional power cost, I was loosing 3:1.
(Extra power cost $4, I earned about $1.2 from the other coin).

Revenue is not profit.