i think it's a waste of money. moonlights are overrated. you can't really see anything that's happening in the tank with them on and it does nothing for the inhabitants.
i'd also like to share an experience i had with a chinese knock-off fixture from ebay-
i had a 30 cube at my girlfriends house, which i bought one of those fixtures for. 250 watts with pc
actinics, over an oceanic 30 cube should have been a TON of light, right? it couldn't even keep zoanthids happy. they grew really long, because they were stretching towards the light. i changed the bulb out for a few different higher PAR bulbs thinking it was the lamp that was the problem, but i concluded that it was the ballast. although it fired the bulb, it did not push it to capacity. you can see in the few pics in the thread below how the zoas changed.
Nurse Smarty Pants' 30 gallon cube : Members' Tank Specifications
these fixtures are similar to the more expensive ones, but not
the same. some folks who have them would tell you their tanks are doing great and they are fine to use, but i've never seen a mature sps
reef with a cheapo ebay fixture over it.
the ones that use them and have successful tanks have swapped out the ballasts for icecaps or sunlight supply units, and definitely changed out the bulbs.
after all that, i'm not sure how good a deal they really are.