A recent visit with Spanish researchers and packers was of interest.  Virtually the whole industry uses a snapping method to harvest fruit.  It is faster and often leads to fewer fruit rots than with clipping.  In a past article by Reuben Hofshi in the CA Avocado Commission's AvoResearch is a review of the practices and results in various countries.  It was well worth rereading:

http://www.avocadosource.com/Journals/AvoResearch/avoresearch_02_02_2002_Hofshi_Snap.pdf