Personally, any of the US colubrids I've kept, I've used a UTH and rarely any lamps. I do this mainly because the bottom of the tank is where the snake is going to spend the majority of its time and while the average temps inside a tank is usually enough w/o any additional lighting, extra belly heat is probably welcome, especially for digesting meals. Obviously, placing it under one side of the tank is recommended so the snake has the option of a gradient.
I can't speak for everyone, but like Z-Trip, I've been used various types/brands of UTHs for years and have never had any issues. The thing to remember is to raise the tank somehow so A.) the tank doesn't pinch the cord of the UTH and B.) there's air flow under the tank so heat doesnt build up and crack the bottom.