Do you think the hosting costs are offset by the income from being a witness?

For the heater thing. The reality is if your PC draws 400W from the wall that is the same heat generation as a 400W electric heater. It is just as efficent at turning electricity into heat. So (99.???%)

It is just that in the PC it is producing a byproduct of computation while the heater is just a dumb resistive load.

If it works well and the crypto market stops the current downward spiral I will start to explore how far I can push the idea :)

The Kalmx card is great choice though. My games rig has RX 480 and with the test mining I have done with that it can sound like a jet engine as it has blower style cooler. So I knew I had to explore fanless alternatives :)