well you're not giving yourself much horizontal room in your flower chamber. I see you want to put cfls on the sides and grow a really tall plant, which could work if you can keep your plant from growing into them and burning. Side lights will encourage side shoots to grow, which means you will have a bush on your hands.

honestly I don't think this is the best use of space. why not put your smaller chambers on the bottom (side by side) and make your flower chamber on top. This way you can flower more plants.