Hmmm... 1997. You'd think that in 20 years the scientists and others connected with CCR would have opted for a different gauge, if one was, overall, more suitable, considering the community is volunteer, all ages, all backgrounds, etc. They've spent much time evaluating various devices. Yet the 4" remains standard, despite all the 'research' and comparisons various folks have done. The gauge remains standard, because, across the board, it's the best for all, and if there were a real issue with the 'measurements' it reports, I guarantee you it would be changed... too many institutions from NASA to NOAA and all the other alphabet letters rely on CCR.... rest easy... and play by the established rules and standards.
The cardinal rule that CCR mentions over and over, especially in severe weather, winter storms, etc... is "Stay Safe"... forget the gauge if need be... that's what comments are for... don't risk yourself on ice to measure frozen if unsafe... don't go out in a hurricane to check the gauge.