I know for a fact that if you measure the temperature of a mercury vapor spot vs a zoo med basking bulb the zoo med measures hotter. Did you like them? What do your setups look like? What kind of chameleons do you keep?
I liked them. My cages are VERY densely planted allowing the chameleons to hide from the UV and heat intensity. I've used them on Veileds and Panthers. And yes I liked them but I rarely see cages that I would want to use them on as many people do not plant as densely as I do.
You can find photos of my cages in various past posts of mine. Im working on compiling a documentation of the cage design and construction.
I write in past tense because I'm not currently using them, though I am awaiting a shipment of some to me. My last MV bulb lasted about 18-20 months- with seemingly great UV output. Though I haven't gotten my UV meter yet.