Good point on ensuring the brake pads are fully seated into the clips. If not, there is no telling what sounds or problems will arise. It takes a pretty good effort to get the pads to snap into the clips and engage properly.

Don't overthink this. For us, we run oem Avid metallic BB pads on the road, off-road we are now running EBC HH. The EBC pads squeak and squeal a lot, but stop well and do seem to get trashed in one wet ride. OEM pads have stopped well for us, seldom squeal or sqeak but are crap in the wet. Almost as if the pads dissolve.

FWIW, we beat the crap out of brakes off-road, maybe not long descents but high speed to near stops on our training grounds. Let's say the oem brakes off-road have screamed for mercy, but always stop.

If the pads or disc are wet you will get shudder. If the caliper shifted and / or is able to flex the mount iit can shudder or make all kinds of noises and vibrations.

I no longer run spherical washers on the Co-Motion, need to convert the Ventana when time permits. Over time, my experience is the calipers will move on the spherical mounts even when tightened properly.

Also, on your low time bike, have the spokes brought back to spec as far as tension, loose spokes and discs will do odd things too.

PK