I haven't used them, but a friend of mine does. He has 250watts over his 180. Amazing growth, but he's not happy with the colors. He's tried 14 and 20K bulbs I believe.
Coralvue makes every type of bulb for aquariums out there, MH, T5, VHO... Which ones are you asking about?
Their halides are pretty good, but for T5's, I like Korallen Zucht and ATI's better, in that order.