All the induction cooktops I've used (both builtin and plug-in) have been REALLY useless at temperature control. Even the heat settings leave a lot to be desired, they are very coarse.
The control freak is orders of magnitude better at temperature control. I suspect it is not only the design and quality of the sensors, but the algorithms used to maintain the temperature (probably good PID).
There are two sensors:
a small glass covered sensor built into the center of the heating element that is spring-loaded and gets the heat off the bottom of the pan.
a second plug-in sensor with a cable, that can be attached to the side of a pot using an insulator gadget and suspended in the middle of whatever you're cooking.
Another pretty critical part is the "programs" you can write.
For example, you could make a "hamburger" program to bring the pan up to temperature, then beep to add the burger, then flip it later, then remove it and do another.
I would assume those would be mostly useful for frying/searing meat, vegetables, and eggs with little oil. As soon as you have more liquid in the pot you won't be able to control the temperature by measuring the temp at the bottom.
Do they work well with different pans?
That sounds like an interesting engineering challenge! Assuming we have a stove with a fast-acting heat source (e.g. induction) and high-frequency thermometer (> 1 Hz), what can we learn about the contents of the pot/pan?
I'm thinking: dump a set amount of energy into the pan (say, 0.5 seconds at "power boost" level), then watch the thermometer. Do it several times, with varying pulse lengths (say, 0.1 to 1 second - you don't want to burn anything on the pan, nor wait too long for it to cool down). This should give you a good idea of the pan's step and impulse response, and - I think - you could guesstimate what its contents are - particularly, if there are any liquids in it, and what they are. Then, continue with normal cooking, but keep a continuous record of power output vs. temperature measurement, and possibly occasionally pause and do a round of such pulse tests again.
I see no obvious reason this wouldn't give a stove quite good control authority even in the presence of liquids, including those that are added or naturally seep out during cooking. I also don't expect any of the appliance companies to ever include this level of sophistication in their products.
I find it very convenient. It's not perfect, because of course a sensor looking at the bottom of a pan can't be, but in practice we've found it very handy for the boil function (bring water to a boil @ 100 deg, drop back to 95 and hold there; making candy/fudge that requires holding around 80 degrees, making proper custard for things like creme caramel. The higher temperatures are good for things like dealing with meats, since I can dial in a temp and not fuss over what's going on.
The thing that has surprised me is how relaxing it is to use - as I say, I feel as though I'm fussing over what I'm cooking less.
That said, they're accurate to only 5 degree increments at best, and I wouldn't try using them for something like a sous-vide replacement.
