Ebb and flow, loose hydroton outside of net pots needed?

Yeah I think like others have said, the main benefit would be to block light into root zone

The roots should stay down deep enough to avoid light if you have 4 or 5 inches. Only problem with using the clay like this is the cleaning the roots out for the next run, and you may end up with a lot of green algae on top. So as Wicked says., it would be best to cover and block light. Keep your ppm and ec levels correct, and you should have a great grow.

I have never seen someone use a flood table like this. The best results I have seen from a flood table use fiber mats and a cover to block light from the roots. Your setup can definitely grow some buds, but blocking light from your roots is the most important part of it