In my 8k I have to go with air cooled hoods, the ceiling is 8' and I like to do 10g pots, 4-5 per light depending on strain. I felt like gavitas would have been tough to keep cool in a smaller room and you have to keep the hood 3' above the canopy so that wouldn't give me much room for the plants. 4x4 for each light. The way the ac/de is set up, air cooling works fine. Doesn't affect the bulb temperature at all which is what causes problems. I use ushio pro plus de bulbs and nanolux de ballasts.
The nanolux weren't my first choice but all the gavita remotes and phantom de's were sold out and my hydro store wasn't sure when they were going to be able to get them. They said every one and their mother with a warehouse is eating them all up. I go to a relatively large hydro store too, they got 3 locations. I tried getting them in sacramento and humboldt, no go. They told me sunlight and hydrofarm didn't have any in stock and were waiting for them to be shipped from over seas. But anyway the nanolux have been working great for almost a year now, no complaints yet.
This video shows the par levels with 3 different air cooled DE reflectors, really good information and it shows that the ac/de isn't affected by the air cooling unlike its competitors.
In my larger setup I use gavitas, but I have 15' ceilings. Same thing there, 4x4 per light.