I can't think of anything that breaks between version 5.0 and version 6.0 so if 5.0 already works then it should be okay.
There are a lot of breaking changes between 4.0 snd 5.0 though, e.g. AllowDocumentFunction, although I don't know if they are used by the library anyway, I suspect not.
--
Joe (
Microsoft MVP - XML)