Hi I have the same question.  I haven't updated since feb 2015 partly because of every update i kept loosing functionality.  Also what happened to the cheaper eBay update cards online.  I don't see anything less than a $1000 and could of swear saw them for around $600 before.  

 Hello tompidge like you I have not updated. I last updated just before the major system update. My tool works fine. I can reload all early software and run both at the same time. I turned my wifi off and have not had any system problems. The tool has lost functions. Yes I do not have 2016 software but I am not working on these vehicles right now. For me the tool works well and I want to keep it that way. I bought an update card for the 905 just before the major update and never used it. I would sell it for $300. Unless you got screwed by autel and have to update to fix software issues I would run with what you have. There is no telling where autel will go in the next year. EDE65 tried to make this a great tool but in the end it was not to happen. I still like my tool but will not update it and lose functionality. Keep what u have.