A lot of times single piston calipers will wear one side faster even with free slides. The piston acts on the one pad first and the force is all on it to push the caliper sideways to engage the far side. So the piston side pad engages ever so slightly before the far side pad.
In this case I don't think that it would help. The issue is that you're running a new gear against a used gear. The mesh patterns aren't going to be quite the same and that's where you'l get the noise.
There's not really a need to since the crank spins. Adding more holes would just up the cost of cutting them and add more time broaching. Several of the original iterations had a welded on handle and I never found myself withing for more angles.