Tarun and Krishna thanks for your inputs. It was really helpful. At my client we are currently on SP6 so cannot use change manager. However I tried out sp8 developer edition on AWS and was able to play around with Change Manager. I have to do some more analysis on the system privileges like
REPO.MODIFY_CHANGE,
REPO.MODIFY_OWN_CONTRIBUTION, REPO.MODIFY_FOREIGN_CONTRIBUTION etc.
Thanks,
Aamod