Rational Change vs RTC ( change and configuration management)
One answer
I must admit to not being able to answer completely, as I do not own Rational Change, whereas I own and use RTC CCM, also in conjunction with DOORS, and very soon with Rhapsody.
I believe, though, that you should state better what you wish to achieve, which products you wish to perform Change Management for and, as you hint about configuration management, what is your aim also for that.
CCM is pretty good for our purposes, having plans, a customisable lifecycle etc. We are successfully using it to perform change management of DOORS where it is vastly superior to the internal CPS, really there is no comparison.
We use it also in one projects for tasks and coding, but is that what you are looking for ?