Actually this is very simple - but for hours I could not understand why the sync kept "deleting" and "recreating" certain exactly same folders (tunes) during sync - I have a number of examples Rodrigo y Gabriela and Chris de Burgh are two. My tags differed and some albums were Rodrigo Y Gabriela and Chris De Burgh verus - Rodrigo y Gabriela and Chris de Burgh - PLEASE note the CAPITALS. As iTunes agent runs, the album folder REPLICATIONS are good to the target, and each time the sync creates the .mp3 in the "correct" folder - repeatedly, i.e. chris de burgh - it does not matter about CASE, BUT... the precursor routine that establishes "differences" is CASE SENSITIVE, and removes an album if the "artist" case is different. SO ALBUMS with artist Chris de Burgh and chris de burgh belong in the SAME target folder , BUT the case difference means iTunes Agent deletes the "none conforming" case tunes, and then recreates them in a "none case sensitive " folder in exactly the same place!. - hope this helps