Just remember that although you lose depth in the tank, you gain height to mount coral directly on. Most of my SPS is mounted on the wall of my 24" tank. Softies and LPS get the bottom half of the tank. You also gain a very significant amount of surface area for bacteria wih the front and back of the wall plus whatever rock is incorporated into it. My tank with rock wall has been up since November and my nitrate has never been anything but 0 even with heavy feeding and I attribute it to the wall).
Drawback is if you get algae that's not nutrient-dependent (I'm looking at you, bubble algae!) you can't remove the wall to deal with it. I don't recommend not having it attached to the wall and sealed because of the toppling danger, and detritus buildup.