I have the one like Midwest sells. At 2200W it is a little close to the edge for a 20amp circuit. I brought 6.5gal to a boil (from 100F) in 70 minutes, going from mash tmep to boiling would be 50min. I did trip the breaker at one point though. I'm going to try it on another circuit but at 2200/120=18.3amp this is close to the limit and I don't want my wiring to be getting hot and melting or causing a fire.
Literally the day after I bought this I saw 1000W bucket heaters in a farm store for $35 apiece. My 2200W unit has a nice controller though and will work in a plastic mashtun if you want to use it to regulate temps.
I just bought a $60 1800W induction cooktop, going to see if that isn't the way to go electric during the winter.