I don’t use 1000w anymore but I avg. around 4 lbs off 2400watts (4x600w) in a 8’x8’ space [3lb of it being the quality I require from flower for patients 1lb- usually goes to making various Extracts.) I do a lot of training through veg from mainlining to monster cropping though.
And I’ve pulled a low as 12oz per light (600w) with some of these designer strains. The first run I did indoor was off a 1000w HPS DWC and some nirvana seeds (blackjack, white widow, papaya, and ice) bud, I messed this grow up and still pulled 1.5lb< out of a 3’x5’ in a non reflective space with nothing but Flora Nova and a ph vial.
They both appear to be quite experienced growers and I am sure they have a plethora of useful information they could share with you. A lot of growers I know get stuck in their ways when they have consistent successful runs. You’ll find your rhythm too and a lot of what you’re going to learn you’ll learn from trial and error. Gather your information from many sources there is always more to learn.