I run 24/0 and have 'normal' m/f ratios. And once my plants are evaluated, I keep mothers anyway so that becomes moot after the first round with a new strain.
My reasons for running 24/0 rather than 18/6 are:
-Better temperature control
-No need for a timer, which can fail or burn out
-I can visit them any time
-I don't feel like lightproofing my veg room
-I can leave it completely open on hot days to stay cooler without worrying about light cycle interruption