You may want to calculate the DEM error using different approaches, e.g. phase, PhaseVelocity or excluding noisy acquisitions. Currently the dem error file is always called demErr.h5. An --outfile-demErr option would allow to create e.g. a demErr_phaseVelocity.h5 or demErr_phaseVelocity_exclude10.h5 file without overwriting demErr.h5.

Could even go a step further to add phaseVelo automatically as a suffix (demError_phaseVelo.h5).