Your math is flawed.
Explain to me why a C8 plot would earn 20% less XCH / month ?
The whole point of plot compression is to have a smaller plot with the same result. Every K32 is equal, no matter the compression level.
It’s not, the power draw difference between difficulty 100 and 1000 is almost zero. From 1 to 20 is where you save the most, it’s an exponential decay.
Just plain wrong.
You should also learn the difference between W and Wh, Wh is not Watt per hour, it’s Watt times hour. So a power draw of 10 Watt for one hour would be 10 Wh.
Based on your own claims for power usage, 0.2932 kWh/TiB/month for normal plots and 0.3312 kWh/TiB/month for C8 Gigahorse, we can say farming with C8 costs you 13% more in power per effective netspace.
Assuming that your uncompressed profit margin is 50% (ie. half the XCH farmed goes to pay power bill), we can say that C8 will increase your profit by: (100 + 42 - 3 - 13/2) / 100 = 1.325 = 132.5 % - 100 = 32.5 %