Bored4Long, my opinion of the lighting rigs is based off a four foot fixture with:
2 X250W halide or
4X65 CF fixtures or
a six (or eight) bulb t-5 system. VHO, overdriven lights, etc are all upgrades to be considered when estimating your tanks lighting capabilities.
Case in point, I have dual SE 250W halides over my two reef tanks. My rockwork extends all the way out of the top of the water. I have Duncans in less than 3 inches of water and also at the very bottom on the sandbed (24 inches deep). I would consider the ones at the bottom of my tank to be in low lighting, bordering on medium light. The ones at the surface are in a very high light area. Both are doing well. (But the ones at the surface are easily three times larger polyps than the ones at the bottom of my tank).
I also have 2 Koralia #4 (2400gph total) with another 600gph from my return. 3000 GPH for each tank overall. Divided by 90 gallons for my display tank equals: 33X turnover rate for my tank. So I have Medium flow in my tank. (But on the high end as far as medium flow goes.) I keep mostly acans, chalices, zoos and duncans. So everything is doing great.
I plan to start keeping SPS in the near future, so I will likely add another Koralia #4 so make my flow rate 46X turnover. Then I would have high flow.
I also will add a pair of 110W VHO bulbs to my lighting system when I do the switch to SPS. That should "double up" my lighting and create a high light area that goes much deeper, and would get rid of any 'low light' areas at the bottom of my tank.