I do have digital thermometers, there not shown very well in the photos though. I actually have two, one for the cooler side and another for the hotter side. What your seeing is my humidity gauge, which is analog. I will look at getting a digital humidity gauge tomorrow.
The only issue I have at the moment with putting my UTH on the bottom is, my stand is too small for the cage and won't allow for any escape of the excess heat.