The roots die at the edges and self prune. Whereas in plastic the grow down along the edge.... It's a preference thing really, imo. I like the plastic myself. Different strokes. The plastic require more up pots because of the larger rootmass, I think? Gloria is in a 3 gallon. So
Self-pruning was supposed to be better at developing mass because every root tip that died told the plant to send out another root, as opposed to having an existing root get longer in search of more space and soil. I guess if you keep up-potting in plastic then the roots never run out of room anyway!