I am just starting my first grow with a Sun System 315 vertical all in one hood/ballast with a Phillips bulb in a 3ft x 3ft tent.
The tent is 6.5 feet tall, so I don't think I should have any issues with height. This is my first grow with any 315 cmh, but based on the research I did before buying this light it sounded like vertical mount was maybe a little better for the 315 bulbs?
I am really loving the light so far, runs quiet and cool. The tent is 78-79 degrees with no vent fan running, and light output and balance in the 3 x 3 space is great. Plants are literally just sprouting, but I am excited for this grow with the new light. I am not expecting it on my first grow with this light, especially since this is my first grow in a whole new setup (and in quite a while), but I have seen multiple reports of people pulling 3/4 -1 lb in about the same space with just one of the Sun Systems 315 Vertical.
It has been 5-6 years since I was growing last, it's fun to get back into it and have all these hi-tech new lights. Between the ever improving LED and the new sexy 315 LEC it's a huge step forward for the industry.
I'll post some pics once the grow gets going.