I had a 4' acan lighting fixture on a 6' tank and then another 6' tank with 2 evo G1's. The tank with the acan lighting was very dull and def not enough light...that sides were super dark (even though they said it would work out perfect the way I was hanging it). Only thing I would say good about them...the par was higher on the acan lighting than the evo g1. I would NEVER spend the money on that fixture though...I would go with AI's all day long if I was going to spend the money.
sorry to be a bummer, but that's my educated opinion on the fixture.