So, I finally got into vegetables, which means much higher temps than meat/fish, and my first probe conked out. I think it has to have something to do with the hotter water. It still works temporarily sometimes in cooler water. Anyway, I was bitter, but Auber Instruments was pretty cool about it and gave me a 40% discount on the replacement. I frigged up and told them the wrong model number, and they were cool about that too. Really good customer service I have to say.
BUT it still sucks that replacement probes are $30 for a thermistor, some wire, and a stereo plug, so I wanted to find an alternative. It's possible I'll figure out how to build a probe for the Auber controller, but in the meantime I bought a Johnson Controls pre-wired controller for like $80. I figured it wouldn't suck to have a second rig to cook things while I have one controller tied up with experiments such as cooking short ribs for a week. My wife agreed not to divorce me (for now) as long as I keep the second rig in the garage.
The Johnson controller has a much simpler thermistor probe, with leads that have to be wired into the controller. I think it will be much cheaper to replace. It also looks very sturdy. However, the thicker wire doesn't fit as well under a lid as the Auber probe.
The Johnson is nowhere near as user-friendly as the Auber. There are internal jumpers that have to be set to get the correct operating mode (heating vs. cooling, etc.), which requires taking off the faceplate with a screwdriver and decrypting the instruction manual. Not major surgery, but definitely not plug-and-play like the Auber, so I can really appreciate what Auber have done to make something closer to a kitchen appliance as opposed to industrial equipment. Also, it's ugly and the cords are big, while the Auber is svelte and looks good on a kitchen counter. On the plus side, the Johnson is configurable for cooling modes, so could be used to control fermentations (lager) and god-knows what other crazy projects I may get myself into down the road.
Unlike the Auber, the Johnson is a so-called "bang-bang" controller - it turns on the heat at a particular temperature setpoint and off at another point. There is a tiny bit of customization that I haven't played much with, but at the end of the day it is either "on" or "off", which gives much less precision that the Auber, which can cycle the power quickly to achieve "partial power." I set the Johnson to click on at 129 and off at 130 (F) to cook some short ribs for a week in my garage. The initial overshoot was pretty severe - something like 138. But once I added the ribs it seems to have calmed down and spends most of the time between 129 and 132, with occasional excursions to 133. This variation wouldn't be acceptable for some applications (fish), but it meets my needs for long-cooking tough cuts of beef. I will get some veg in there eventually at 182 and see what happens - I expect wild behavior but who knows?