I use them to light larger cages that have other sources of UVB, such as with my mercury vapor bulbs.
To be honest, I don't really see a huge difference, but it does make the plants grow and the chameleons I've housed with them have done well.
For extra illumination and brightness, I'd actually suggest their
Ion bulb instead. Nice, bright, and I like the color of the light better - it's a lot more blue toned, looks more like natural light to me. The Vision lights have kind of a yellow hue, which makes sense as the wavelengths produced are very heavy in the yellow section
Maybe for forest or nocturnal species, the vision light would be a better spectrum to use than the Ion bulb.
I use these bulbs on my large vivariums; I don't see them having much use in the traditional setup for chameleons, with their tube fluorescents and basking bulbs.
-Jen