I got a couple packs of GTH#1 3 years ago from Attitude. Germinated 15 seeds. All came up. Got 9 females. All of them were pretty potent, and had a better than average taste. Pretty uniform Sour lemony taste in some with a hint of anise/licorice. Very low yield. Long internode spacing, typical of a Sativa dominate plant. Varied a lot on flowering time.
For sure had to be supported. They were fairly similar, though some were thinner than others, but varied a lot for flowering period.
Some were done in 65 days, but I never had 1 go past 80 days.
I vegged in 5 gallon containers with 2 1000w Hortilux HPS, on 24 hours. Flowered in 20 gallon containers and 3 x 1000w Hortilux.
Best plant produced 8oz. Got 49oz total.
By comparison I am currently getting 2- 2.5lbs x 1000w Hortilux from 2 plants in 20 gallon containers of Mr Nice Super Silver Haze. 75 days flower. Though some can go 63.
Potency is about the same vs GTH1. GHT1 may taste a little better.
I also agree with pure/more Sativa type plants, a bit less light can be a good thing. I start with 12/12, and the last 3 weeks cut back to 11/13. I really don't think 1 hour less per day does a lot to hurt production, but I have read it has a positive effect on the chemical profile of the plant.