As far as I understood the point of the scrog screen is to train the plant under it then flip to bloom. Some Farmers will flip to bloom leaving the screen 3/4 or so full and allow the stretch to fill the screen then after the stretch you let the buds form above the screen. The manner in which you are using the screen is more like a trellis.
Trellising is a good way to support your plants though. It will help hold and support the stalks/branches when the heavy buds start to form. It also helps to keep the canopy even and not cluttered.
That's a pretty niffty idea with the trays! Need to get yourself a tray! You'll wonder why you didn't do it earlier once you see the easy in use.
Also I wouldn't be running your runoff back through the soil too much. When you water it flushes the crap and salt build up within the soil to wash out the bottom. So in essence your adding the "waste" to the top of the soil. Not going to kill a plant but just a thought. If you flooded a table and watered from the bottom you would see the waste collecting on the surface of the soil instead of flushing out the bottom. I prefer to water from the top, bottom, and foliar. This way I'm not building too much crap in the medium. Last thing ensure you are flushing your medium at least every two weeks to clear all salt build up. This will help a lot. Lets just go from here ;)
:passingjoint:
Cheers,
Crom