Liquid media has better nutrient diffusion and uptake rates than semisolid media. In semisolid media, nutrients are depleted in the local root zone but remain untouched in distance areas.
In an experiment with Banana, Root Stands with a rocker developed twice as fast! With the Root Stands in static liquid there was a slight speed advantage, there was more uniform rooting than in semisolid (100% of explants rooted), and we didn’t have to wash gel of the roots!