The issue is that if the room temps are not almost exactly stable, the thermostat will not keep the UTH at a stable temperature.
I did some unofficial tests of my own with the zoomed reptitemp 500R. I will NOT ever use one again.
Unregulated zoomed UTH -- 121F
Regulated zoomed UTH with zoomed reptitemp500R- 114 (this is after letting the unit set up. The temps fluctuated greatly in the room the snake was in). 114 was not an acceptable temperature for an UTH for me. I took multiple readings over the few weeks it took me to get my thermostat (a johnson control). 109F, 111F, 112F. It never really settled around 95. It was always above or below and i had to watch it like a hawk.
Spending the extra 45 for a johnson or ranco was completely worth it. I check my thermostat every few days and Ive got a temp gun and accruites on the heat tape in my racks.