From the forums:
http://forums.terracotta.org/forums/posts/list/0/226.page
If a shared object is serialized, it possible to observe unresolved reference values. I believe the reason for this is that field values are read using sun.misc.Unsafe.getObject(..). Specifically in java.io.ObjectStreamClass$FieldReflector.getObjFieldValues(). This method of reading field data will bypass the DSO mechanics for resolving fields.
I don't think fields that are DSO literal types are affected since they are never unresolved.
I'm not sure about logical collections -- although I guess they are okay since they implement readObject/writeObject in terms of their iterators which do flow though DSO goodness.