As long as your DNS is fully functional with the new host name and routing is working as it should, changing the host name will not cause any problems.
Important Considerations for Password Synchronization
Once the hostname has changed, a reboot is always required for this to take affect on a computer running Windows. The starting up of the Quick Connect Service upong reboot will actually trigger the creation of a new service connection point in Active Directory. The old service connection point, however, is not removed automatically. You can manually remove the old service connection point using ADSIEdit.
Doing these steps will create a new service configuration file containing the connection information of the new host name, allowing for password synchronization requests to be properly routed to the Quick Connect service.