You may encounter the following error when attempting to restore a database using version 5.1:
Failed to read backup files. Error message: Invalid parameter @with supplied.
If you are connecting to a box with 5.1 LiteSpeed installed on it from the 4.8.4 GUI then you should fail. That is because the 4.8.4 UI adds some parameters (which were accepted by 4.8.4 such as "@nounload")- but are not accepted by 5.1, remotely.
Upgrade all servers to 5.1 to resolve this issue or use the 4.8 GUI ONLY to restore to SQL servers which have 4.8.4 LiteSpeed still installed.