Grow efficiency? advice please

Ok I am currently growing in soil, 15 plants under 3 1000w hps. I was just asked by another med patient to grow for them. This means 15 more plants!! What I'm wondering is what would be the most efficient way to grow with a limit of 30(currently)? Should I switch to hydro? I was looking into an ebb and flow setup and liked the concept a lot, but would I want to run a sog type setup with only 30 plants? What could I look to yield if I tried this? I'm mainly asking because my 15 pots fill my 8'x12'x9' room as is. But if moving to hydro means taking a knock in yield I'm leary. Any suggestions are welcome...I was even thinking about an ebb and flow with perpetual harvest. A 3'x3' table would save a ton of space and only require one 1000w hps so I could dedicate the other lamps to a mother room. I already have a clone room with its own lights(flouros). I just want to be as efficient as possible and I've only ever grown soil.

Thanks everyone

personally i would stick with soil if you have a good source of water around, thats the hardest part is watering 30 plants, i would set up a 20x 20 roomand grow em to a pretty nice size maybe 2-3 feet before flowering a lot of watering wher with a hydro setup you just have to worry bout the res not crawling through a jungle watering or maybe set up an automatic watering system for the soil plants but than your getting closer to going hydro hmmmmmm i always liked soil ive done hydro too but after doin that for a year or 2 i felt better going with soil hydro you could loose a whole crop easily if a pump breakes or somthing els is off, soil the plants will be there as long as you water em properly so idk i vote soil if you have the means to water it all

That's the problem, I'm currently restricted to the size room I already have. I wish I could expand.

doesn't really sound like you need to grow 15 more if you can't expand but I don't really understand what the problem with hydro is most people would probably say it would increase the yeild. 30 plants is enough to do a sea of green with you could always just harvest like 7 plants every 2 weeks. That's 7 clones going in every 2 weeks for a 8 week strain comes to 28 plants plus your mom(s).

oh yeah you can just build a small grow cabinet for the veg room so it wouldn't be a large expansion.

What could I yield per 7 plants? Or let's say even 30 if I were to not do perpetual on an ebb and flow?
I'm open to any suggestions. I would love to stay with soil too, but as I expand it seems that hydro may be a logical direction. I just never wanted to since I'm not doing a shit load of plants(and I love the challenge of soil growing).

That's it huh? No one has any other suggestions? I'm sure there's a variety of answers that would suit my needs. I just want to here what others with a similar number of plants have been able to accomplish, ie. What kind of set up yield and so on.
Thanks