I've had Schaller straplocks or compatible ones on all my instruments for ages. After getting another Warwick bass which turned out to have the Warwick-specific straplocks on it, and the cheap Schaller clones I bought being rubbish, I decided to treat myself to Schaller S-locks. I already have a set on the Variax bass so I didn't expect any issues. Fitted the strap part fine, but when I tried to fit the pegs to the bass, I ran into problems. Unlike the older Schallers and the clones, the peg and screw form one piece, with a hex hole to take an Allen key in the centre of the peg. The hex cutout was poorly cut on both, on one the key just turned in the head and the other was so sloppy a fit that any attempt to put significant pressure on the key would have rounded out the head. This was a decent key, incidentally, and a second key, a bit from a decent socket set, showed the same issues.
Strings Direct were the suppliers and were very helpful, and sent out replacement pegs. These went on OK (still a bit of a sloppy fit, I wouldn't have been happy using bolts with that sloppy a head on a bike). Then one of the straplocks refused to go on. Took the pegs back off and went home and ordered a set of Boston clones. Oddly, when I retested the Schaller straplocks, they did go on OK, so I'm keeping them in reserve, but I won't be splashing out £25 on any more sets when I can get Bostons for under a tenner.
The inconvenience was somewhat multiplied by the bass being at the rehearsal studio 20 miles away, and me travelling by motorcycle (not anticipating problems) so that did delay things a bit.