If you want to pull yourself over your xxx POINT FOUR! hours in a Moth thats fine by me. I haven't totalled mine but maybe 3 figures both in slats and without slats. So you maybe stall 2 knots less with slats, big whoop. They're just another unnecessary item to maintain.
They are a visiual and audible sign as to the wings AoA
I also need slats to tell me how much energy I've got over my wings.