I used Schaller's for years...All my guitars get Schaller S-locks. Best in the business. No noise and they are extremely secure.
I had the same thing happen on two guitars with the Dunlops I installed. NEVER again. Even the old Schallers are way better than the Dunlop version of straplocks.Only Lock I ever had fail was a Dunlop "duel lock" - the little ball bearings didn't engage and the pin slid out - I caught the headstock before it hit... Those are the only ones I'd recommend you skip...
Planet Waves makes straps with the locks built into them. You just place some over the strap buttons on your guitar, click them shut, and you're good to go.
I don't like to take the straps off of my guitars. I also like each guitar that I use much to have it's own strap. The Planet Waves straps with the built in locking device work well and being plastic they don't hurt the finish.