The svn converter actually compares the common parts of the repositores to find anomalies, with manually inserted clearingpoints for those anomalies I have inspected and reacted on. I hope you have a similar system for the git repository to scrutinize the information received from the CVS repositores (which can not be trusted as a matter of prinicple).
Another repository could theoretically lead to new anomalies which would affect the existing clearingpoint, but if no changes are done directly in the repository it _should_ not happen. Besides, making a new CVS repository would remove the blowtorch to actually go through with the switch, meaning it will not happen for another 2 years again...
