Ah yes that's Bob for you. He's a good guy and his product is fantastic qaulity but is VERY uh, insistent on how his product is the best there is compared to all other options and you are making a dangerous mistake if you choose otherwise <_<
If you let him he'll write you a novel why all UTH's and competing RHP's are a hazard lol
Personally I've always been a fan of the UTH + RHP combo. Been working fantastic for me and many others who have gone a similar route. I just like being able to control the hotspot without compromising ambient temps.
When I used only a RHP I found my warm ambient temps were getting way too warm for my liking just to get the hot spot I wanted. Especially since I was starting with a 24 x 24 cage (a divided T12) which really didn't give me much room for a good horizontal heat gradient with just the RHP. The RHP itself was practically as big the top cage half so you can get an idea how things get a bit complicated.
Adding a UTH gave me more flexibility keep everything better balanced, and as pointed out earlier it's good to have a back up on hand. Plus you can go wrong with a Herpstat 2 :p
PS. Why is typing on mobile so hard