Upgrading - or just an opportunity to learn more about the tribulations of software?
I am comfortable with my current version of Mac OS (Mountain Lion); however, the feature that allows for app expansion only within the current monitor space that Mavericks offers is very appealing.
But at what cost is an upgrade, even when the software is free? There is always a cost of time and effort needed to implement the backups, learn any nuances that changed in the work flow due to some engineer knowing a better way for you to perform a task, and just the typical stuff that can just go wrong (thank's Murphy for never taking a day off.)
But I'm going to do the upgrade and learn what needs to be learned, and to then lick any wounds that I incur along the path, because the feature of having the screen expansion local to the monitor that the app is residing on is just too good to do without.