I know there was at least one change in the RSV because of discoveries in the dead sea scrolls. It was in Psalms in a particularly difficult passage. I don’t remember where I read it though. But at the time, I checked it out and saw the clarity that the discovery added to the translation. But generally speaking, I think changes are very few.
The problem is (as I see it) is what constitutes the “best” original text? The oldest? (not necessarily the best indicator depending on the text, although it still is important, considering how relative age might be when compared to the real original.) Most of the oldest manuscripts have significant differences, omissions, additions etc among themselves, while at the same time corroborating (for the most part) the accuracy of the text we currently use.