Various issues exist when trying to sync configuration between sites. This issue is tracking all the outstanding issues related to this topic. Please feel free to add new issues as they appear.
I was attempting to bug hunt some stuff with sun today, and ran into the issue that I couldn't just put his cmi files in staging and import them. I ran into a number of issues one after the other that all probably have issues already, but as an example of the sort of stuff that's generally preventing CMI sync from working, I thought I'd make a patch and drop it here. I stopped after I ran into instances of cache_update table being called because I couldn't afford to debug further, but thought I'd at least provide the exception I stopped at, and the patch for stuff I fixed to get this far. This is intended to be informational. the fixes are pretty much 'quick and dirty'. Perhaps it can help troubleshoot other issues.