okay
@Abhishek I'm testing the PAR now but this will be a very stripped down version until I have more time. It should give you some clarity though.
I turned off my right light and first measured the Drop off in PAR at 11" AWL (SPS PRESET) on my tank. My tank is only about 17" of actual water. Directly below the water surface and center on the fixture I had 500 par. As far down as the Apogee wand would let me go I had 175. So with how shallow my tank Is I concluded that most people should not hang the fixture this high due to the abrupt drop off in par. However for a mixed reef around 20" deep it's pretty good.
@Hydrored if your running your lights at 13" I would lower them. A mixed reef will most likely not be running the sps settings so these numbers will be a little lower.
okay so after determining 11" is about as high as I would go for your "wall to wall" sps system I started to measure par spanning away from the fixture. I measured off the right side of my left fixture. I hope this explanation isn't too confusing. (my wording) My reason for doing this is to take my left/front eurobrace out of the equation and also the black overflow. Basically since the fixture is 18.5" cube and diodes are completely symmetrical we can take the numbers I get and apply it to all the surrounds of the fixture. I would assume maybe a slight increase due to light bouncing off both sides of glass (in your tank). The pictures will also probably help if there is any confusion.
Since your tank is 40" wide and the fixture is 18.5 inches I needed to measure par about 10.75" to the right of my fixture to get you par numbers. 10.75" At the surface avg par was about 45 and at the bottom avg was about 55.
They sound like terrible numbers but I forgot to factor in one thing. If your one row of stratons are bumped right up next to eachother the overlap might double these numbers. I need to do more testing when I have the rocks out in the next couple days to do some aquascaping. I will test more heights/presets and try and calculate how much overlap to expect. Regardless I would say 34" would be the absolute maximum these lights would cover. Also I'm assuming your corals don't go glass to glass. would you say all acros are within a 35" span? If so I think you can make it work.