People on here are using 2 kw water heater coils to act as heatsticks...the immersion circulator would work on the same principle....just a few less watts....11 at 120 is 1.32 kW. 7.5 at 240 is 1.8 kW. 1.8 kW is pretty close to the 2 kW waterheater.
I think it would be awesome for precision control of HLT water. It would NOT be great for maintaining a boil, as a boil is done by pumping craptons of EXTRA energy into the water....(water at 212 does NOT boil....water at 212 with craptons of EXTRA energy going into it boils). Immersion heaters are meant to set the output water temp from the immersion coil at the setpoint. This means it takes a while to come UP to temp, but it will hold that temp to within fractions of a degree.
So, bad for boil, but if you used propane to get your strike/sparge/mashout whatever water close to temp, then immersion heater to hit that EXACT temp and keep it there, that would be pretty cool, I think.
Yeah, it goes up to 150C, or 300F, (which doesn't convert exactly, by the way), but it will NOT boil water. If you want to maintain a rolling boil, get or build a heatstick or a bigger burner. If you want PRECISE control over your HLT temps, use this.