Hey Brad,
Congrats on the switch over, I know it was a heavy hit but it will be well worth it in the long run.
As far as for the spread, I have mine at 4 inches awl since I added another unit. I kept the lens stock just like yours so I can blast the sps on the sand bed like my efflo. To be honest I don't see much of separation from the lighting, although the shimmer on the sand bed does have a distinct difference then the shimmer from halides. You said you have your lights sitting at 6-7 inches which in my mind will give you the spread and the coverage around 10X16 area and if you left it up a bit maybe another inch or so then you can increase that to 10.5X18. If you do supplemented with some T5's, you might be able to get away with 3 for a while.
I think you know my stance when it comes to LED intensity, LED's will produce more par when you compare them to 250 MH but I highly doubt that the a brand new 400 halide are putting out anything less then 1000 par at the water surface which is similar to the sols and that par from the halide is evenly distributed across a large area even on the sand bed. I am not telling you to blast your corals right away but instead lift the sols up a bit and have them around 10-12 inches awl but keep them on the same schedule as your halides so if you run your MH for 6 hours a day then run 100% for those 5 hours on your sol and see how everything reacts to it then lower it in a week or two as the coral transitions over to LEDs.
Let me know how it goes, I am hoping to see you on this side of the water soon.
Rich
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