Was on a LONE4 2006 and had paper tickets, all dated, changed a date with LAN, walked into the office in Santiago, no stickers, no problems at check-in although the ticket showed a different date. While in Australia, called Finnair to change the date on two flights, no prob to do over the phone and did not need to reissue the ticket at all.
Changes showed up in SABRE/AMADEUS at once.