I have a 400 in one 10 square foot room and a 600 in the other 10 square foot room both doing regular grows in soil, and 4 plants in each with 5 gal buckets is TIGHT but the 400 is good light and the 600 is great light. You have the perfect amount of light for that space.
I would just do a regular grow, I assume by style you mean between scrog, sog and regular? In that room I'd try regular or scrog(screen of green), although you really don't have a height issue with 8 feet. You can learn some LST(low stress training) techniques so you can force your plant to grow the way you want to. 6 medium strain plants will be tight but doable in 15 square feet. I have to assume you have a separate mother and clone room. I do, but in both my other rooms I continue to veg the clones under MH for a week or two more after they have been cut and begin rooting in my dome with a t5, then I switch out the MH with HPS and flower both rooms at once. I'm guessing the room is like 5 long x 3 wide x 8 tall so if I'm not too stoned here that is 150 cfm needed for full air exchange under a minute, but i'm sure you have that covered. Good luck