As far as the flimsy-ness of the UTH vs a human heating pad, you have to think about it from a design point. The UTH is designed to be put UNDER a tank that is NOT resting directly on the heater (if you read the directions it'll normally say to use feet or spacers to raise the tank up so you're not crushing the cord, putting undue weight on heater, and for airflow), whereas the heating pad is designed for an average person 105-200lbs to be able to lay on it.

With this in mind you can see why the heating pad may be built with materials for a higher load, however it is also not designed for constant use. I have had quite a few heating pads go out after a couple days to max of 2 weeks under constant use before I went with racks and flexwatt. However all of my lizards and display snakes use UTH's, under normal regulated use (ie rheostat or thermostat), they last for atleast a couple years. Will you find defective products that have issues, yes, but you'll have that under virtually any product.

I have no experience with the substrate, however how does it react to water? I see it's not a clay so it shouldn't clump up, but cotton isn't exactly the best thing for holding moisture without molding. Just because a product COMES sterile, doesn't mean it cannot allow bacteria and mold to grow in it later. #1 reason why people use Cypress is because the trees themselves live either IN or very near to water and takes quite awhile for mold to grow on it.

Not bashing on what you were told, just stating another opinion with some other facts.