Would you believe that I have recieved much grief over the definition and what field-assembled means with contractors (pool & electrical) as well as inspectors.

Prior to 2002 there was a difference between field built and packaged spas. Now there is really none as far as GFCIs are concerned.

The requirement for GFCI protection for spas was first put into the 1993 code edition with an enforcement date of Jan 1 1994. It was again revised in 1996 but only included self-contained and packaged equipment assembly units. It was 1999 when the section had a major rewrite and CMP-20 also included field-assembled spa's to require GFCI protection since some had the opinion that it wasn't needed because it wasn't included in the old code year writing.