I have a 2x2x6 ft Grow Box, using 2 Mars 300 watt panels for over 1 year now. Very happy with the lights and the yield.
Lots of info about the lights so I am just going to add this…
Leds don’t have the spread of hids or reflector lights so I look at the size of the unit plus a couple inches on each side as the footprint. Different brands have different sweet spots (focal points) so some are more effective with a little wider footprint than others. It would take two Mars Hydro 300s for that area at about $80 apiece but one platinum would do it cuz they are longer. Not sure what the Platinums cost. Vipar Spectra also makes a longer light that might accommodate as a single unit.
Thanks for all the info, I have alot to think about.