First impressions on the Pro Stop pads, the fit is not as precise as the Textars that were there before. The backing clip that holds the inside of the rear piston is not nearly as strong and the clips did not fit the piston diameter. They were too small. In hindsight I should have bent them outward for better contact. The pad backing plate also was less precise and the friction material contact area appeared to be slightly smaller than the Textars as well.
Overall, the fit of the pads were just a little bit sloppy, but it doesn't appear that this will affect braking performance. I do worry that the fit may cause noise.
One thing I was going to do against the service instructions was to lightly grease the guide bolts. I noticed that when pulling them out they had some extra deposits on them, and no grease. So why mess with a system that already works well? No thanks. I just cleaned up the guide bolts. However when you are dealing with metal-on-metal guide bolts and slides, grease is necessary (like in the front E30 carrier for Girling calipers). Also, the notch for the pad sensor may have an incorrect pad backing thickness. I didn't use a new sensor ( I don't care about brake lining warning lights). Maybe a new sensor would have a tighter fit, so I can't conclude that it is the pad's fault.
I have yet to drive the car to report on performance. I don't believe in a bedding in procedure, just drive the car carefully for the first handful of miles until they naturally bed with normal use.
Luckily all 4 Textars had about 1mm (by eye) pad material to spare. No rotor problems.