I think that there is no advantage. Or at least so little to be negligible.
I think someone roughly my skill level would probably burn themselves trying to slop a ball more than they would benefit from it that there is a high probability that it would work out to be a net disadvantage for them.
But ... if both players are of the same skill level, and both players play as if slop did not count (i.e., not trying to slop in shots), but one player gets to count slop on the rare occasions when it occurs and one player does not, then the player who gets to count slop has the advantage in the long run.