I would like to get NI's formal position on this question. It was my understanding that DVR's of arrays are an efficient way of avoiding array copying when branching would ordinarily occur in their absence.
This seems to be confirmed here:
However, there appears to be some (very outdated) chatter with a contrary view:
There are normally lots of changes in LabVIEW from year to year; so if this contrary position was ever true, it may no longer be so.