I have always followed the if you don't want to lose it, back it up. I have been doing that for an extremely long time, I'm looking at the last paid version Drive Image from Power Quest, before Symantic/Norton bought them out and put the good bits into Norton Ghost. That cost £39.99 quite a lot in 2002, I also bought their Partition Magic around the same time.
Prior to that I would be doing manual data backups of volatile files/folders with a small program called Mirror. I still use that even now, several times a day I fire off a batch file with mirror commands to backup to a second drive. My drive imaging software would also include that backup location.
In all of that time I have used it many times and not once as a result of a problem with Avast. Some have been for minor issues, that I estimate would take longer to do manually than run the bootable restoration CD and point it at my backup location and last backup.
I keep the last 6 drive image backups and I run it on Sundays and I'm just about to run it on my systems.