Talend Open Studio is one of the best tools I have used in recent years but for the purpose of apply data masking I have been using Data Masker.
I do however agree with Kootstra_a that replacing values with a random or. Lookup/replace - to maintain consistency - using the map component is an inexpensive approach it wont always stand up in you test use cases.
Check out
http://www.datakitchen.com.au/ for info about data masking, data masking methodology, data discovery and test data management.