If you read around, there is some writing about them wearing/scoring the bores on the sides. Perhaps carbon crud gets embedded in the surfaces and acts as an abrasive.
I am looking at the same thing: press fit pins on floater rods. I have been considering a small set screw from the underside with red Locktite, and perhaps a matching groove in the piston for it to lock into. The pin does not seem to take a lot to hold it in place. I've been wondering what problems (and thus disasters) might come from that approach.