Shit man, you wil get more than 20o grams, I was thinking 500 + with those 1000 watt lights.
Yeah at the very least. If he has CO2 and good nutes I don't see why he couldn't go over .5 grams a watt. If you have a perfectly good environment I don't see why you couldn't get 500 grams or more per light. Shit with 2000 watt you could get a pound and a half or more personally. Each of those 1000 watters should get you at a minimum .5 grams per watt. That's a conservative figure too.
If you clone your best plant, use top quality nutes, have proper temps, PH, EC, no deficiencies, and use CO2 I'm betting you could go over .5 grams a watt.
wow 2000w for 8 plants. If you have the room I would let them suckers veg for at least 8 weeks. top them correctly. Get them big and fat before you start flowering. Make sure you do not harvest them to early. Let Them Ripen before you harvest!! You do it right and you will harvest a hell of a lot more than 500g
4 large plants under a 1000w setup is actually the ideal amount of plants for that type of setup. You want each plant to have at a minimum 100 watts of light per plant however you really should be giving each one more than that if you monstrous colas. I wouldn't place more than 4-6 large plants under a 1000W or 40 very tiny plants ala see of green style. I also would only veg till they were 1 to 1.5 feet tall. Those fuckers will stretch 2-3 times their size during fruiting.
P.S. I plan on using 2 1000w for my grow once medical MJ passes in my state.