Test Complete!
I think it's fine, Phil.
First I cranked it up without any water in it and decided to shut it off when the thermo-gun registered close to 500 degrees -- and counting -- while aimed at the inner liner.
Then I dumped in 8 Corningware Electromatic cups worth of very cold water and set the control at 300. It was boiling in just a few minutes. I had to turn it well into the Simmer zone to get it to cycle off and stop boiling.
Set at about 1/3 of the way into the Simmer zone, it held the water just below boiling, cycling off at 175 and back on at 165. Just inside the top 1/3 of the Simmer zone, it kept the water at a medium boil, around 190. It didn't want to cycle off at that setting, and although I'm no physicist, I think that had something to do with just having plain water in it as opposed to a food mixture containing a considerable amount of solid mass.
I'm also impressed with how the outer surface remains relatively cool to the touch, unlike any of the slow cookers I own.
The way this thing heats -- much faster than a standard slow cooker -- I'm betting that the crock on mine got cracked because the previous owner exceeded the red zone setting with the crock in place.
I'm going to call it good. Now all we need to do is arrange to unite it with your crock and you can give it a whirl using real food with and without the crock in place.