ryan--

I think that in theory, your idea is great. The plants would have tons of room, drainage would be better, and soil would not compact as easily. This is in a world of "perfects". Here in the "real" world are the drawbacks--
1) if you ever want to move your plants you are just in a bind. If you decide to do any construction/addition of equipment/change your grow medium or method then you would have to transplant or wait till you harvested your girls to make these changes. As a relatively new indoor grower, I can ASSURE you that you will make many many changes and/or additions to your grow area, lights, vent sys, CO2--the list could go on and on. These changes create dangerous conditions to your plants that are best handled by moving your ladies to another room or area while working & testing the new improvements to your grow room.
2) PESTS= ever noticed a critter on ONE of your babies? If its in a container you can simply move it away from you healthy plants to prevent spread. This also is applicable to male plants. if, like me, you intend to produce your own seeds, then you cannot use any males that happend to sprout in the same area as your girls.
3) FLUSHING--depending on your set up, Im gonna assume that flushing would be very tough if not impossible with your proposed method.
I have a few other reasons but I think you get the point. The reason I could fire these off is because I did some research on this method because I truly liked the idea. I even had a baby pool picked out that was 8ft in diameter and about 2ft deep. I had intended to drill 1/8 inch holes for drainage all over the bottom and then put about 1.5 inches of pea gravel to make sure it had great drainage. I was gonna build a frame out of 2x4 lumber to support the pool over top of another pool to catch the drainage. You could use a very small pump and filter to remove any water from the drainage catch pool. I was all set to start and then I chickened out. I have a room that would just leave me no room to move around in if I would have used this setup. I am very happy with the 5 gallon bucket grow method. The roots have AMPLE room to grow and currently my papaya strain girls are 3ft tall and almost 3ft wide with no stakes or strings to hold them up. This lets you know they have healthy roots and are not constrained at all.

If you decide to do this, I would be happy to email you my detailed plans with drawings. I even have 2 different sizes planned out and materials priced. Let me know.

BamaGrower