Smart pots~ I have harvested in a 3 gallon and 5 gallon, 2 harvest each so far. This is facts I have seen so far~ The root mass for starters, well when you pull the plant straight out of the pot (after harvest, lol) and split the soil in half you will see there is no roots 1/4 inch from fabric in. From there the roots start to get full and thick all the way to center.
When it comes to moisture containment it requires more often watering.
I have many wonderful, fat plants being the roots mass is being pruned at the ends. Also I take a 3 gallon and roll it down half way, stick in a clone and keep it fat and bushy until I am ready for her to take cuts then unroll her and fill in with fresh FFOF.