Yeah, Wat he said!
With one notable exception....the NEW Kirst Safety Cylinder has been approved for use when loaded with five rounds. (See the February issue of the Chronical) However it still has a draw back in stages that have a required one round reload on the clock because you will have to fire at least one round, then stop and reload. With a "six shooter" you can draw the weapon, pull to half cock, turn the cylinder by hand enough to stuff in the required one round reload, and commence ta shootin.
With the Krst Safety Cylinder you would have draw, fire one round, empty and reload one chamber, and then commence again!