Yeah I have the two 315s on each side of the de and that's my plans for the run. Problem is the more I work with this 630, the more the plants are showing me signs of too intense of light.. and I already have it 3 feet away. The closest I got it was 24 inches I believe and the morning after my plant was not happy. Have been dealing with other problems with the plant though so maybe coincidence, maybe the light was too close. Either way I raised the light after that, the plant was so dropped that morning. That specific plant is not shown in these pics. 6 weeks old, I have it in a tent in a separate room until I can figure out the problem.
Another interesting thing to note though is even though ppfd is low with that de, everytime I have to work underneath it for whatever reason, it burns my skin pretty good, I ducked a couple feet under the 315s just a bit ago and I don't get that same sensation. So there's gotta be another factor here, probably the one you pointed out.
I'm afraid I may not be able to finish with this de but we will see. I can't say if light intensity is the problem with my bigger plant, I highly doubt it(just got this plant isolated today and made three changes, it actually seems to be getting better in just hours, I'll probably make a post within the next day or so on the topic that I think could've been the issue, still learning). But my seedlings are showing borderline too much light @ 3 feet, I know seedlings are more sensitive though so hopefully that's it. Ceilings are only about 6'10". I'm thinking flowering at around 2 foot canopy (from the floor) and hopefully finishing around 4 feet. That's probably about the most I can afford height wise with this de. And that's if I'm lucky I'm thinking. Ill be trellising though and lst'ing so that should help fill the canopy at a lower height