Just got my G2 170 in the mail today. Didn't have much time to play around with yet but did run it for a good 30 or so minutes and had no flickering issues and the heatsink fins are all straight and true. The fixture has weight to it and feels pretty solid. Didn't hear any rattling or anything like that. I think the mounting legs are kinda ridiculous. I have the unit laying across my tank in a parallel fashion and smallest the legs can to clamping my tank lip is a good 3" inches hanging over on each side. Either going to have to sport the provided hanging kit which seems nice or modify the legs.
The fixture sits on a 48" long tank and there's shadowing in the corners for sure. Especially up top in the corners where my equipment sits. It naturally hides the powerheads which is fine by me. It's going to take a little getting used to coming from the T5's and a box full of light, and instead going to accented rocks and corals with shadowy corners. However it does make the tank look more natural like something out of the reef I suppose. Fans are super quiet moonlights look good and the shimmer is a very nice bonus since I'm not used to seeing them with the T5's.
The only con I see so far is the mounting rails built into the fixture to accept the legs are bent inwards a bit. This means the legs don't sit totally flat and look pretty stupid. I haven't messed around with it yet but it looks like they can easily be bent out.
Pictures tomorrow night as my camera batt is dead.
Would hanging the fixture a few inches higher still give decent par and eliminate some of the shadowing?
MIchael