Yea, so I made the RDWC a few years ago after using flood/drain trays for years. I wanted a better root system and was failing with F/D. Plants grew OK, but in the end, the roots were not supporting huge growth.
Here is a shot of a root system:
Shortly after, I also switched from 2000 watts of HPS to 900 watts of COB. Both were great decisions, IMO.
I based the RDWC on the 6XL. The cost for the Current Culture system is about $1500- $2000. I made a replica for about $600. I used CC bulkheads, tubing, and pumps. I bought black totes with attached (and hinged) lids. I can grow one to three plants per tote.
Here are a few Gogis:
I love the system, but it is a lot of water to move. I have a garden hose that goes down to the room to fill it and another hooked up to a pump to pump it all out. I used to shop vac the water up and lug it out once a month. This system is WAY better! I also use Fertmax for the system, which is considerably cheaper than the CC brand fertilizer and exactly the same. My cobs keep the room below 80 degrees in the 90+ summer heat.