I never buy any software that is version x.0, but after there have been a few updates to fix the inevitable new-release bugs, I plan on upgrading. At $20 (to upgrade from version 5), it's really a no-brainer.
The most important feature for me is the faster file copier and the use of Apple's FSEvents API to eliminate the need to read every file on the computer in order to determine what's changed since the last backup.
Disclaimer: I do not work for Mike Bombich. I'm just a happy user of Carbon Copy Cloner and I wanted to share the news of a new release with those who may also be interested.