Gavita says their 1700e is a direct replacement for a 1000w HID. In a 4 x 4 area. The 1700e is rated at 1700umol, but is really 1781umol.
A 1000w Hortilux HPS is 1880 umol
The Gavita is 645 watts.
Going by their recommendation, thats 40.3w Sq/ft to put out the same or close umol as a 1000w HID. Using the best diodes of course.
Also IMHO many LED light manufacturers overrate the area their lights can cover efficiently.
A 400w ( Technically 387w ) LED would be the equivalent to a 600w HID. A 600w HIS will cover a 3 x 3 area, and is 66w Sq/ft. I use Hortilux as my model because on average their bulbs have the highest umol rating for HID bulbs, except the Ushio 1000w HID bulb is rated at 2100umol. The same as a DE Gavita at 1150w. It will cover a 5 x 5 area depending on the hood.