I'm running 3 racks with flexwatt and two racks with THG. I don't notice a huge difference between the racks, but as I update and build new racks I'll be using THG. It heats up much more slowly and is a quality product for the reptile industry. It's still just as dangerous as flexwatt if it's not regulated, so don't kid yourself on that.
As for wiring it. If you don't want to buy the tool order it wired...