In case you are not aware the U.S. NGS – National Geodetic Survey has announced an updated North American Datum of 1983 (NAD 83), which is being referred to as NAD 83(2011) epoch 2010.00 – to be precise, or is that accurate?
This adjustment will affect some 80,000 NGS passive control marks positioned using GNSS. The median adjustment is about 2 cm horizontal and vertical at the 95% confidence level. Since the new realization yielded ellipsoid heights that are inconsistent with the existing geoid model, a new hybrid geoid model, GEOID 12 was developed.
If you are searching for centimeters over long distances you need to care. For more information you can visit the NGS website.