It is always important that a copy of the config is saved elsewhere on a server to facilitate a speedy recovery should there be a catastrophy. While Cisco Routers and Switches can recover from a crash as long as the running-config is copied to the startup config. There is every reason for it to fail as it did on one of my Catalyst 3750s.
There is a lot of automated config backup solutions available for free/opensource. Its worth knowing a manual backup procedure as well.
Any software is pron to have software upgrades either to fix a bug or a Security vulnerability or even for the fact the software has reached its end of life.
While Network devices and appliances are no exception, the upgrade process requires a lot of precautions and measures are taken to ensure that the upgrade process doesn't fail or cause problems post installation. Upgrading Cisco IOS is no exception. Care has to be taken to ensure that the newer version is tested on a test bed before deploying in the production network especially if we are talking core network switches and routers.
Kiwi CatTools automates configuration backups and management on routers, switches and firewalls. It provides e-mail notification and compare reports highlighting config changes. Supports Telnet, SSH, TFTP and SNMP.