I'm sending my Glock 17 Gen 2 to Glock for some service work. On the warranty form they list a "frame upgrade" as one of the services. Can someone tell what they do or what it entials? Also, they list "refinish slide". Is this this something that is worth doing? I've had similar services offered by manufactures (not gun) in the past and it turned out not be worth the extra cost. Thanks.