I should wait until later as I’m a contrarian. Multi-cookers are fundamentally flawed. Like most multi-function tools they don’t do anything particularly well. How would you feel if you took your car in for service and the mechanic whipped out a Leatherman multi-tool to work on your car?
We make a LOT of yogurt and do some fermentation - mostly pickling. The best “multi-cooker” is a pot backed up with canning jars.
Here is yogurt, adapted, as taught to my (I kid you not) by Tibetan Buddhist monks. Heat your diary to about 180F (85C). If you don’t have a thermometer that’s about where it just starts to steam but isn’t even getting bubbles around the edge. This is hot enough to kill unwanted bacteria and also causes some long-chain protein molecule changes. I’ve used whole, 2%, and 1% milk successfully both pasteurized and UHT. The monks use yak milk when they can get it. Let that cool to about 115F (45C). Stir in your yogurt starter. I use commercial product with live cultures but you can use the specialized powders if you like. This cooling ensures that the desired bacteria have the best temperature regime to replicate. I bung the whole pot into a cold oven with the light on. The monks stick a ceramic crock under the saddle blanket of a yak. Darn handy, those yaks. 10-12 hours later you have yogurt. If you like Greek-style yogurt you’ll have to strain it and will lose about half your volume. I make half a gallon at a time and store the finished product in quart Ball jars.
I responded to a timed challenge from a friend who insisted an Instant Pot was better, whatever “better” means. We timed contact time and using a pot took half the time of the IP. Double blind taste test with wives was a tie.
We’ve pickled cucumbers, beets, radishes, onions, and various odds and ends. In my experience (and USDA guidance https://nchfp.uga.edu/how/can6a_ferment.html) temperature is not particularly sensitive. Regardless, I use an immersion thermometer and an IR thermometer (why not? I have them) and have no problem keeping temperature within a degree or two on a crappy electric cooktop.
A combination of personal experience with a number of multi-cookers and reading the manuals of more just reinforces my conclusion that multi-cookers are a solution looking for a problem. Which leads to engineering.
One consistent shortfall of multi-cookers is that if the power so much as blinks they turn off. You lose the batch (you can probably save yogurt - maybe). I have yet to see one with conformally coated or otherwise protected printed circuit boards. If you drip down the front of an IP there is a good chance you’ll short out the board behind the display. If you spill something on the counter you can short out the unprotected board underneath. I’ve yet to see a multi-cooker that is as easy to clean as a pot.
If you want to buy technology, remote thermometers that notify a phone app are pretty cool. Multiple timer apps (I’m using Timeglass on iOS) so you can have a bunch of timers running with little labels are great.
Then there is counter space. I’d rather have a bigger cutting board than a bunch of devices blinking at me. YMMV.
I do believe there is a role for slow-cookers. The manual off-low-high ones just keep going in brief power outages. There really is nothing to go wrong. Very elegant piece of engineering.
Others will vigorously disagree with me.