Hoping to get under 80% attenuation for this attempt but not sure to what degree a 2 degree change in mash temp will really change...
when is the last time you calibrated your thermo at mash temps?
How do you calibrate a thermometer at mash temps?
that's the tricky part. You have to get access to a thermo that is to be trusted in the 150-170 range and check it against that. Usually this means a NIST certified old school glass and alcohol model.
It may or may not be worth it. I personally have not done this with any of my thermos I just play around till I figure out the mash temps that work for me with my equipment. I calibrate at boiling on occasion and once in a great while at 32* but that's kind of a pain in the butt too.