Don't know about the most yield part of that statement bong, but I agree with soil causing fewer headaches. Other then the actual harvesting and the once a week spray for pests I don't spend more then 15 minutes a day taking care of my soil grow (9 plants currently, 12-14 normally), and i don't need to worry about power failures or a bad pump wiping out my crop in under an hour. I don't need to worry about water PH all the time, I have a lot more leeway when it comes to nutrient issues, and I don't have the extra expense for pumps, air/water tubes, PPM testers, etc.
How large a space you need is really influenced on just how big you plan to grow your plants, and how bushy they are. I started out using a 10' T, 3' W, 12" L closet for 6 plants set 2 wide and 3 long, but ended up deciding to move them out into the open room and save the closet for a veg space once they started getting close to 2ft tall. They height wasn't the problem-the width was. I had leaves pushing up against the walls and doors of the closet on most of the plants by the 18' mark, and since I've moved them out into a wider area they've gotten even bushier. They should end up being between 5-6' tall at harvest, and I'm guessing the things will be somewhere between 2-3' wide based on the way they are growing.