I have been recycling my config file since BETA 5 with no issues. I would do fresh VM builds every so often in between updates.
From my experience, it has been solid for restores from build to build.
I have a basic config with nothing fancy on the routing and networking side. Just some nat's, aliases, rules and some settings, but way too much to redo from build to build.
So for peace of mind and if you want to start fresh, do a complete new build and then make a backup.