hairy_hen said:

Since the '93 version comes from a source that is at least a generation older than the theatrical stereo mix, it isn't much of a stretch to imagine that a few more sound effects were added to their final mix that had not been there previously. To me, this suggests that the elusive 70mm mix of Empire quite possibly did not contain these sound effects either, since it would have been done first. If true, the mystery of the missing snowspeeder effect may at last be solved. :)

Sorry if I don't understand what you mean here, are you suggesting that the missing snowspeeder effect is a thing that's been brought over from the 70mm audio track? It sounds very logical to me.