I'm sure the idea has been floated out there before, but this is a pretty big deal for users. I can't begin to imagine the amount of hours lost because of a lack of autosave. I know that Revit provides save reminders, but often people are either in mid command and don't want to save, or they just aren't ready to save/sync back to central yet.
I propose an autosave that works similarly to Revit Server. The idea is that Local files still exist in their standard form, but an additional autosave file is created each time a new local file is created (for users at my firm, this should be every time a file is opened). Periodically the autosave kicks in and only saves changes made since the last save/sync/autosave. This would cut down on the size of the changes need to be saved.
I would be willing to add a couple minutes to a large project load/save times if it meant that I also got autosaves.
We should also be able to set a frequency for autosaves as well as turn it on/off. Mine would always be on, but it would cut down on complaints from people who don't want to lose the time autosaving.