Here's a couple of posts that I posted a while ago on another forum:
For YEARS I defended the Dunlops- more or less because that's what I was using, I liked them and they're easier to lock in and unlock. After several straplock failures, including the one that almost killed a 45 year old $5000 guitar, I looked at the mechanics of it, the Dunlops have either 2 or 4 spring loaded ball bearings supporting the weight of your guitar (depending on the age of the Dunlop lock you're using) . That's it. Those bearings fit into a trough on the female end of the mechanism- that's all that holds your guitar onto your strap. The Schaller has a cast metal cup that's held in place by a spring loaded plunger. Even if the plunger fails, the cup is more than capable of supporting the weight of most any guitar. (any guitar a human being can carry around) If the Schaller fails, it's going to be from the nut and washer coming undone. Loc-Tite, clear nail polish- something to keep that nut from loosening- and it's pretty much idiot proof.
This is new for 30 Aug 06:
When talking about that "trough" in the female end of the Dunlop unit- gunk can get in there- not allowing the bearings to grip properly and then there's the physics of the weight of the guitar wearing on the "upper" portion of the male end.
I just took these pics- granted these are older locks, but the wear is the same...
You can see how much toll the weight of guitars has taken on the shaft.
Notice the concentric rings from the different "female" ends that have been used.
