Nother useful tool is
Object Filler and Object Dumper Download Site . I've found cp_merge to be very unrelieable.
You can use the object filler/dumper to dump the objects and then import them back into the other system. This gives you better control over integration of objects and duplicates etc... It does mean you'll need to manually re-create rules, but as part of the consolidation you should be doing a review of the rulebases anyway.....
Good luck.