We've probably had our Leupold 6x30 bins for 15 years - generally, its job is to sit under the front seat of the car for opportunistic viewing. What will I gain by updating it to a new set of Kowa YF 6x30? Coatings? Case? Objective covers? (My covers are long since lost.) We have no complains about our current set, but wonder if we're missing anything.