I bought the 3.5lb disconnect, extended slide lock and LCI for my gun, I still kept the old ones just in case because I'm indecisive. No, I don't have any spare springs or the stuff that I SHOULD have on hand for a 15-year-old gun but I live 4 miles from Glockmeister's store so it's not hard for me to get replacements.
I've also purchased the Glockmeister extended takedown lever and trigger spring but don't use either. The takedown lever was scraping up my holster and the spring didn't change my pull weight at all. Now even the stock flat slide lock lever is on there because I had a bad habit of putting my thumb on it! gee why won't my slide hold open? gun must be broken -.-