Primary Conclusions
The DANTE radiation temperature tends to be higher than the witness plate’s, especially when the pointing is small. (i.e. the beams are relatively near the LEH.)  This difference can be big (~15 eV). This represents a difference in the incident radiative flux of almost 50%.
The main exception is with low albedo and deep pointing.  Then the witness plate radiation temperature can actually be somewhat higher than DANTE’s.
The witness plate incident spectrum is always harder than the DANTE spectrum.
The LEH lip makes both temperatures higher, but the DANTE temperature gains more than the witness plate temperature (typically 10 eV vs 5 eV).