Is there any (preferrably open source, freeware or cheap) tool to
optimize away superfluous ACEs (ACL entries) for files and directories?

I.e., our file servers are Win2k based, and thus support inherited ACEs.
But still, presumably because of historical reasons, gazillions of files
and directories have explicit ACEs that duplicate what would be
inherited from some ancestor anyway. The tool would find such ACEs and
remove them.