I'm stuck in a build, the goal was to make a light for a 2x4' tent. 400watts of Vero 29SE cobs with one per square foot is my desire. My problem is which driver to run 4 of these cobs, I don't want 4 drivers, so I am going with the 36/37.7v D cobs from rapid. Would like to stick with meanwell drivers, and run them 1.4a. So my question is: 
HLG-240H-C1400B's will for sure run 4 Vero29se D's. The HLG-185H-1400 is really close but you could have problems on start up if it is cold. Safest route would be to run the 240h's. Really 50 watts a square foot is way over kill you would have to run Co2 to use all that light. You could get by with half that light especially running one cob per a square foot. Runnning 4 Vero 29SE C's off a HLG-120h-500B will give you 32watts a square foot more than enough to flower with and they will be more efficient then the D's.
I always go over kill because I can always dim. I also have a co2 system I can use if I want to. The way I look at it is if I have the space to expand I will still have enough light for a 4x3 grow in a 4x4 tent with room equipment and a sealed environment.