hi sour power,
G/w measurements are irrespective of light numbers or even bulb wattage.
1 g/w means for every watt of light used(be it 400, 600w, 1000w or more) you get 1 gram in return. G/w measurements alone don't mean much though without stating the timeframe because getting 1g/w , say 600grams from a 600w light , in 4months of 12/12 is only half efficient compared to 1g/w harvested in half the time , 2 months of 12/12 that is. I believe you get my point
If you get the NH dialed in and work with a pheno that yields descent NH can certainly give 1g/w but will do so in a timeframe of ~3.5months of 12/12 ..Top yielding strains like Critical Mass can yield also 1g/w..but do it in less time..around 2 months 12/12 . This is why NH is not a plant that will yield as much as other strains per kilowatt/hour indoors..Outdoors she can become huge and yield massively if she gets some veg time and of course is grown in a good environment.
Veg times will be determined by plant numbers as well as other factors as you know but if you intent to grow 10 plants per light dont veg for too long. 10 plants per 1k light sounds good.
This is how I would personally do things.Start the seeds straight under 12/12 or 11/13 , within ~ 3-4 weeks from seed you will know the sex of the Nevs plants. Keep the females (and males if you wish to use some) and take at least 1 or 2 cutting from each plant (from all plants).
Put the seedplants under 18/6 to put them in veg state as soon as you have taken the cuttings.This way you will turned the flowering seedplants that have showed sex into vegging mother plants for future use.Plus you will only veg and flower/finish plants that are of known sex.
You can now flower the already sexed cuttings straight under 12/12 or 11/13 as soon as they have started to root.. This is something Shantibaba also recommends for NH (to flower n finish clones instead of seedplants and flower the cuts as soon as they are taken from the mother plant-clones come in faster than seedplants and also have a more manageable structure and are great for indoor rooms).
This way you will not only avoid spending energy on males and you will also finish the plants as fast as possible and get a better idea about how each pheno will grow/flower in your future runs with the keepers (as you will grow the keepers in cutting form in the future).
This is how I like to do my selection and have used this method with several strains lately incl haze hybrids and seems to work fine.
The best thing to say to any grower that is running NH indoors is too keep the plant/s profile low , this is what really ensures a good harvest indoors with HIDs as the light intensity drops dramatically the further from the light bulb. So if one wants to veg NH for a long time , prepare for some serious topping/training-LST , if left to grow naturally this plant can get 8-10ft+ tall easily .
l33t