It is all still experimental, so no one really knows what is going to work best.

At least for me, it is very hard to hold a scrog grow within 2 to 3 inches. It is best to stop training before 2d week of budding and there will still be some uneven growth after that.
Getting LEDs to really work, especially without using a focusing lens, you should be within 1 to 3 inches of the top. . Making the lights adjustable is not that big a deal, so I just went ahead and incorporated it into the design.