I have a handful of RB panels, and I got a Pro Heat panel about a year and a half ago to try it -- I like it. Works well, no problems. I will likely buy another if I set up more caging. After using RB thermostats for a few years, I was...uh...not exactly brand-loyal, so the switch was easy.
Cons: They are white in color; to order, you need to contact Bob and tell him cage size and temps needed, and he recommends a size (PITA); they are slightly more expensive than RB (75w 12 x 18 was $105 + $17 shipping last year).
Pros: they are made in US; they are in stock.
http://pro-products.com/pro-heat/