I am currently growing a single plant outdoors (on a balcony), with an AutoPot.
The substrate is 50/50 coco/hydroton, with a 1-inch layer of hydroton at the bottom of the pot. No airdome, no air stone.
The copper-plated marix disc is in the bottom of the tray, I can see a few root tips through the bottom of the pot, but nothing has grown into the tray. The copper seems to prune the roots effectively.
Other than that, I can only say that I am thrilled with the results so far. It's truly a hands-off system. I can only visit the grow every 2-3 weeks, and the 47 liter tank (about 12 gallons) is more than able to supply the plant for that long.
It was a problem plant that I put into the AutoPot, and it's a semi-outdoors grow, but everything works more than fine. The baby looks really healthy and vigorous (about 3 weeks into flower right now).