Ok, back from the LFS. Heater is off. Old thermometer says between 82 and 83 degrees. New stick on thermometer says 80°F. I bought ZooMed digital, (which that I have brought it homes I've learned gets bad reviews on Amazon for not lasting long), and it tells me 80.8°F. Since the heater is rated at ±1°F, I think I'll wait the full 24 hours before I crank it down a touch.
The research into heaters has been interesting, yet annoying. 20 years ago, Ebo Jager was the brand to buy. Seems Eheim bought them and sold them as Eheim Jager for a while, and now there is no Jager line. The new Eheim ThermoControl has replaced all previous heater. My Google searches showed me that people were, in general, unhappy with the build quality of the Eheim Jager as compared to Ebo Jager.
I found a bunch of glowing reviews for the MarineLand Stealth Pro, only to find out there was a safety recall on them, and Marineland has discontinued the line.
Visi-Therm was bought by MarineLand a while ago and their products are long gone.
Is there really need for this much iteration needed in Aquarium heater technology?
I'm just grateful that Hagen hasn't tried to improve on the Aquaclear hang on tank power filters. Those things have pretty much been the same since 1978, when they first came out.