I think people who are running serious additives i.e. Colored UV coolants + anti-corrosive agents are having these issues. Like here. So if you run pure distilled + silver killcoil like me and many others, you should be fine.

That was my first thought also, that the people with Acetal blocks will have no clue IF there was any corrosion unless the took the blocks off and apart, which is the biggest PITA. I have the acrylic ones and they seem fine. I think there may be buildup in the RAM block but I do not believe that is corrosion, maybe that stuff that comes off the hoses accumulated there..