Most surveying applications should not be significantly affected because the changes in relative height between adjacent bench marks should be less than 1 cm.  As stated above, the absolute height values will change much more, but this should not be a major concern to the surveyor.  The greatest problem the surveyor will have is ensuring that all height values of bench marks in the project area are  referenced to the same vertical datum, preferably NAVD 88 and labeled correctly (metadata).  Other agencies’ bench marks, e.g., COE, FL Department of Transportation, FL Department of Environmental Protection, and USGS, were incorporated into NAVD 88 by NGS as these agencies provided, and still do, their data in computer-readable form.  However, the leveling data associated with over 500,000 third-order bench marks established by USGS have not been placed in computer-readable form and do not have NAVD 88 heights.  In addition, COE has established hundreds of thousands of bench marks across the nation which do not have NAVD 88 heights.