See wiki page: https://cwiki.apache.org/confluence/pages/viewpage.action?pageId=97553895
which is about experience in interoperability.
Mike Beckerle created a branch which automatically detects tests that use inputValueCalc/OutputValueCalc and hiddenGroups, and skips them, also doesn't run negative tests.
This is on github at https://github.com/mbeckerle/incubator-daffodil branch daffodil-2028-crossTest.
It does things like globally replace all encodingErrorPolicy="replace" with encodingErrorPolicy="error".