Migrating NLS_LENGTH_SEMANTICS from BYTE to CHAR

ORACLE RDBMS Version: 10.2.0.2.0

1. My dumps are in BYTE length semantics.
2. Altering system NLS_LENGTH_SEMANTICS=CHAR has a limited effect (only new objects are created with new semantics).
3. Trying to alter existing schema objects to CHAR semantics efficiently render schema unusable - from my experience.
4. Any export/import operation retains length semantics of the source without options to alter.
5. One of the possibilities of altering data successfully is to create a new schema with definitions altered to CHAR semantics, e.g. by extracting and changing DDL from dump file, and then importing data onto newly created schema skeleton.
6. Other methods are data pump, and dblink, with the former failing to import all of the SQL data, and latter... I didn't try.