I just realized you can get finer control of the temperature if you use the Celcius setting instead of the Fahrenheit setting. Its hard for me to look at C though so I just made a chart that converts it into F so I can quickly glance at it to see.
If you use F setting, Difference Setting of 1 degree F:
Set temp 100F, heat turns off at 100F and on at 99F.
If you use C setting, Difference Setting of 0.3 degree C:
Set temp 37.5C, heat turns off at 99.5F and on at 99F.
So there is 0.5F difference between the two. Just note that if you change from F to C, that some of the other settings get changed back to default.
If you use F setting, Difference Setting of 1 degree F:
Set temp 100F, heat turns off at 100F and on at 99F.
If you use C setting, Difference Setting of 0.3 degree C:
Set temp 37.5C, heat turns off at 99.5F and on at 99F.
So there is 0.5F difference between the two. Just note that if you change from F to C, that some of the other settings get changed back to default.