I have many relationships/connections in the design departments of several reputable piston companies, not one of them said that they are finishing pin bores to a specific 8-9 RA, or are being asked to do so.

Maybe a lower tier piston company is involved in that, but I have no connections at any of those, nor would I have any interest in buying any of their products anyway.

What I stated here and earlier is the real world, based on real world results in a competitive racing environment (where the real R&D is done).