Most of the commericial designs seem to be powerful 80 to 100 watt units on a small platform of between 1/2 to 1 square foot. I believe this concentrates the light too much.

I am now thinking smaller units between 10 to 30 watts that plug into
overhead motherboards that supply power and help duct heat. Motherboard would probably be about 2'x 2' aluminum and would provide up to 180 watts to supply LEDs and fans. There would be multiple plugs, so units could be custom positioned to fit needs of individual gardens. Also they could be repositioned as needed to accomodate different stages of growth.

This modular type design would also allow for upgrade designs in baby lights. Sort of a plug and play setup.