So far the best (by far) solution I've been able to find is to use ArcGIS to manipulate the elevation values prior to letting C3D at them... I created a fully metric version of the DTM, where the elevation is also in meters. C3D dutifully follows my coordinate system transformation and blindy converts the meters to feet. (and now that is okay.)
ArcGIS can be a great way to solve problems like this. Nice suggestion.
Infrastructure Suite/C3D 2013, LDT 2004, Power Civil v8i SS1
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RADEON 6450, 1 GB
Global Mapper is another great tool for doing this as well.
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