you'd be a better grower than I, I've never reached one gram per watt, not really even close. The caveat being I grow in soil, and NOT for yields. But pretty sure even if I tried I couldn't.
kudos to snapsprovolon for his success, that's impressive.
I usually get around 700-800 grams with 1200 watts.
My strains aren't HUGE yielders though, it's just for me, so taste and quality are more important than numbers. If I had a monocrop of a beefy indica hybrid, maybe I could, but I like to grow nine plants (three different strains) under two 600w lights one MH and one HPS, normally I like to use 1800 watts with 1 2/1 ratio of HPS to MH, but right now I can't. With 1800 I can harvest a TOP quality KG. including the small buds I can do 1200g, I just count the hard nugs from the colas though.
I can safely say that if I get .75 grams per watt, i'm a happy camper.
that'd be 900 grams on a 1200 w setup, also keep in mind that the MH hurts my yield too (but NOT the end-results)