Well, since i've only had my fixture for about an hour and half now, I really can't answer your questions, but I will tell you what I know.
On my tank I can't have it centered because of my hob filter (carbon, chemipure, etc). I will be moving this to another 10 gallon tank w/ no hob filter. As far as the intensity of the light - its bright man. I have 2x 175 watt se's over my 55 gallon, and i can look at them for a few seconds. I look at this bulb for about 1/2 second and i'm seeing white spots when i blink lol.
Since the light is not centered, there is a dim spot on the left side of my tank. I believe this is due to 2 thigns:
1. The light being off centered
2. Since i'm going to acclimate my corals by lowering it about an inch a week, i belive it is just up too high right now to make the whole tank REALLY bright.
As far as evap goes: I would evap about 2 gallons a week on using the powerquad. I will have to test this and see how it goes.
I don't have a par or lux meter, but i will tell you that when i used the powerquad i had a massive colony of neon green zoos. They would never ALL be out at any given time. Within 10 mins of turning on the mh lights, ALL the zoos are out and look real great.
One thing I did notice however, is the heat from the fixture. When touching the top of the head, you definitely have some heat there.. Its actually so hot that you can leave your hand on it for about 2 or 3 seconds and have to remove it because of the heat. I believe jbj should have installed a small fan to remove the heat from the top of the fixture. I know once my 6 month (STUPID if you ask me) warranty is up, i'll be installing a small fan at the top of the fixture to remove excess heat.
Also, some other people have complained about the lack of or not good shimmer lines. I believe they didn't have much surface disruption, as my shimmer lines are great.
If you need anything else answered, let me know, and i'll try and do my best.
Stewie