I did notice one thing with the Kingfisher bass I picked up, the screws would not separate from the stock end pins, so I had to use the Schaller screws which were a tad thinner than the Kingfisher screws, but a toothpick in both holes cured that.
I already have a set here waiting to go into my SE Angelus Standard when I pick it up soon.
I have also gotten away from leather straps, as I hate how hard it is to adjust them by having to weave that thinner part through the holes.
Most of my straps I have now have the buckle on them, and two of my favorite straps adjust via Velcro, very slick.
But yes, all straps have the Schaller part on them to mate with the Schaller end pins.