Cool, well, it seems to be working.I veg under 6 T-5 bulbs to keep them nice and squat but when i flip to my 600 MH I notice I get a little more stretch while yours look like they just stayed compact the whole way.
How much longer till the big flip? Are you going to run both bulbs the whole time or are you going to go all HPS in flower?
I will go with 2-400 watt HPS for flower, although Uncle Ben mentioned in one of his threads to try a MH and an HPs for flower to get big bushes, I will still go the HPS way.
My plan was to take them to about 24 inches tall from the dirt line, and one of them is 19 inches the other about 15. They are growing about an inch a day right now, so in about a week I will do the flip.
The vertical lighting seems to get a lot more light to the whole plant and I think thats what has kept the stretch under control. The lateral branch development is better then Ive done on any plant with horizontal lights.
Also, when i had them under the 250 MH i kept it very close to the plants without burning them and that may have helped.
And of course the genetics play the biggest part im sure.