But to make a long story short. As long as I can remember, 1000w HID, has always been recommended to use in a 4 x 4 area, and is just within the last decade or so, I see some recommending a 600w for a 4 x 4, when, these came out, manufacturers, recommended them, for a 3 x 3 area, and a 400w for a 2.5 x 2.5.
A 1000w in a 4 x 4 area, has 62.5w-sq/ft. A 600w has 66w Sq/ft, and a 400w in a 6.25 area, is 64w-sq/ft. Yes, a 1000w HID will grow weed in a 5 x 5, but is not the most efficient. Same for a 600w,and a 400w. They will cover a slightly larger area, but going by original manufacturers recommendations, they were meant for 4 x 4-3 x 3-2.5 x 2.5 respectively.
Just like when Gavita came out with the 645w 1700e-1700umol+. They say the 1700e, was specifically designed, to replace a 1000w HID, in a 4 x 4 area. The 1700e and the 1000w Hortilux HPS are both around 1700umol.
A 1000w Hortilux Blue-5500k is best used in a 3 x 3, and is about the same umol, as a 600w Hortilux HPS, but with a much better Spectrum.
Leds show us spreading is better from adding, putting 2 x 400w in good reflectors inside 4x4 will have sufficient coverage, 2 x 600w will kill it.
The only time I use a 1000w de is in a xxxxl 1.10m x 1.10m hood in big rooms, putting this kind of lamp in a kinda small reflector and in tents... Just not this bulb cup of tea and won't get you where your going actually.
I just finished a run in a 8x4 with 3 x 400w hps, got like 1200g, adding more plants I can reach 1500-1800 easy, spreading light is key.
In theory putting some 5 x 250w should have gave even better results in that space due to creating more light distributing hot spots(bulbs)
The problem with leds today as it's hard to know their total light output, everything is in ppfd which means final space count and not initial outputof the system.
According to my math in terms of output the 750w hps is equivalent to the e1700 led in output, not in spreading haha, which is close in wattage use.
The 1000w bulbs rank at 170k LM now, the 400v ones anyways, you'll need a 800w led at least to match that.
When cooler temps becomes an issue you understand leds advantage is obsolete to HIDs.
That's why both of them are good in their own aspect, leds are not orientated to to home grower as much as they would like simply because it creates problems for the avg grower.
No one is buying a tent and light system to adapt to the hateful "learning curve" of leds or spend thousands on heaters or AC electrity just to keep temp in check.. thats not logical.
People grow with leds at 70-77F, 70 rh, crazy people, just to be in the hype
Every year a new iphone comes out and people rush to buy, it's same here, just wannabe part of the hype.