I have the analog thermostat control seen on that link, and it has worked out fine. The temperature shifts up and down about 3-4 degrees, according to the temperature strip. I duct tape the probe to the side of my bucket and set the thermostat dial about 4 degrees F lower than what I want. If I want to ferment at around 60-62F, I'll set the dial at 56. The temperature on the strip will then read 59-61. I have taken the temperature of the wort/beer, and it's about a degree or two higher.
My controller has has a copper probe and wire, not like the silver one shown in that link, but otherwise, it's the same controller. The entire wire is a hard copper wire that bends instead of flexing. With time, the wire has a lot of kinks and bends in it. It's not that big of an issue, but I use a compact fridge, so the wire is a little hard to work with when I'm pulling the bucket out to take hydrometer readings. If the digital probe has an insulated flexible wire, which it looks like it does, I would prefer that.