most of the advantages have already been mentioned, you know there female, you know the strain so if you invest in some good genetics or come across a plant you really like you can have it around for a long time getting alot of plants instead of having to buy seed all the time, they are mature and are the same age as the mother plant they came from and can be flowered just after rooting if you wish, which results in a slightly smaller plant versus growing from seed.
they grow faster than a seedling while it may take a couple of weeks to root once rooted they generally grow much faster when compared to a seedling of the same size.
as per the fan leaves never really noticed much of a difference if you veg them long enough they can get large even on clones.