Applications with repository sizes up to twice the threshold can be considered for whitelisting. Migration with a large history can take a long time, and does not have a 100% success rate, although for the repositories that are still within the range, we don't expect any issues. In case the migration fails, it will automatically rollback and access to the SVN repository will be restored. If you choose to whitelist the application, please create a support ticket with the application ID. 

Please note that the limitation has been imposed for a reason, namely that working with large Git repositories is not ideal. You may encounter clone performance issues where a clone takes a very long time, as outlined in the Troubleshooting Repository Size document. Although there are workarounds described, such as partial cloning, addressing the root cause will still require you to do a history wipe at a later point in time.