I have a similar type of light, a GalaxyHydro unit, on my 50 gallon-36"x15"x20", the light is approximately 10"-11" above the water surface and I get complete coverage.
2 would be overkill on a 36" tank unless it is like 24" wide.
I'm currently running mine at 35% white/60% blue and all my corals seem to be happy.
The only caveat is I get a little "spotlight" effect from the red & green LEDs, but removing the lenses as Mr. X mentioned would allieviate that, I just haven't gotten around to it yet...LOL
or I could raise it another 6".
In short, one of those 165 watt units is the best bang for your buck you will currently find.
I know because I spent two months researching before coming to that conclusion.
They are definitely powerful enough with the proper spectrum to allow you to keep any type of coral you want.
If you are set on getting a strip type of light, one with the same power will cost you 3-4 times as much.