with 24/0 you get more growth, shorter plants, and tighter node spacing... which isnt bad if you have good lighting..
the benefit of the 18/6 or 20/4 or any cycle that has a dark period during veg comes from the stretching that occurs during the dark... the stretching the occurs during the lights of period allows for more light to penetrate into the canopy, thus more light for the plant to absorb giving you a stronger happier plant.. since most growers cant max out the amount of light their plants can absorb and use, they benefit from the stretching...