Awesome post! A few questions:
1.) could you have used a dryer cord, larger GFCI breaker and bigger element? or were you limited by the Simmerstat current handling ability?
2.) Would an old stove burner controller work for this? I do not leave my brewpot unattended so I could adjust the knob as required.
3.) In the schematic for the simmerstat connections the outlet connections are labeled ground, hot and neutral. In a 3-prong 220VAC configuration, they are actually ground, 110 hot and 110 hot right?