Personally for that space, i would go with the mars 400w. 4 is ideal, but 2 is still a lot of light. I have 2 x 1.2mx1.2m tents, one with a single mars 1200 and 1 with 4 x mars 400. Both are great, but the later offers more flexibility, especially if not growing ScrOG
Absolutely right!
Multiple smaller lights should always do better than a single large light. It's not like HPS where the 'bigger' bulbs actually put out more energetic light, ie they would travel further or penetrate deeper. With LEDs, they all use the same LEDs so if I have 50 or 500, they all contain the same amount of energy, or penetration power. You have to shift your logic a little when moving from HID to LED.
If I put 200 LEDs into a 24"x24" package, it's going to have a certain coverage area.
If I put those same 200 LEDs into 4 lights, and then spread those lights out, I will be able to get a better coverage with the same LEDs. Granted, 4 of the 200 LED lights would be better, but I'm trying to compare apples to apples. All other things being equal, multiple lights will give you better coverage than a single large light.