Global Mapper 14.2 does. Ive assembeled NEDs and DEMs up to 500 sq miles and exported them as a single USGS DEM. It's not much of a mapping program but it sure does a good job of converting data formats. It will even take the GEO PDF's and convert them to .TIF, ecw, or sid (with ER toolbox installed)
I just tried a 350meg NED took less than 30 seconds to import and export to State Plane in US Feet.