FWIW, another famous Alembican emailed me privately, they use Dunlop straplocks *without* using the locking mechanism. They're physically larger buttons, making it very difficult to accidentally unhook your strap when used like that. But then so are the ones I currently use.
Of the straplocks I've looked at, I like the Schallers best... very solid *snap* when they engage, and as Keith and Coz pointed out, the U-shaped design would still hold even if the lock failed.
I dunno... I mean, bottom line - however unlikely, it's more hardware to fail, and another fastener to make sure is tight. Plus, as a matter of habit, I never, *ever*, let go of my bass anyway. I can't imagine the Vulcan-like mindset changing even with the added safety of straplocks in place, so there isn't really much to lose by trying them for a while.
As a humorous aside, I was talking to another guitar player about this yesterday, who often (for good-natured sport) questions my thing for finer musical instruments. They were like - Are you serious!? You're actually spending time thinking about what strap buttons to put on a bass!? My reply, Well... yeah, of course I'm serious... why would I not?
This just in folks - we're different. I have to assume that's how we all ended up here.