Schaller are fail in strap-"lock" form. Rubbish.
In every strap lock thread/debate it's amazing how many Schaller users have had issues, and how many proponents say they're great if you check this and tighten that and maintain the other after you first install it in a special way with added materials. [EDIT - witness this very thread!].
I've had nothing but problems with Schaller strap "locks" and that's with very limited, and proper, use *including* regular checking since it became necessary due to the ongoing issues until I got rid of them. My basses are far safer with a plain strap, perhaps with a rubber washer, and I move myself and my bass very actively onstage.
Schallers strap "locks";
- squeak.
- come unscrewed over time with use, fall apart and drop your bass.
- scratch the finish of the instrument.
- unscrew the pin from your bass, which falls out and strips the hole while dropping your bass.
- might not engage fully, and thus fail.
- ruin the strap, or won't even fit on some nicer/thicker straps.
- won't fit in most hard cases with the strap lock on, thus necessitating removal and the more you engage/disengage them the greater the chance of the eventual failure.
- poke a hole in the bottom of gig bags if you leave them on.
- prevent you from easily resting your bass with stability on its butt on the ground to lean it against your cab or whatever.
- require you to have the related mechanism on each bass or strap you wish to use.
- time and money wasted in purchase, installation and use.
- etc. etc. etc.
- Pros? None, other than a very false sense of security.