So, my concern right now is whether it is really so problematic to validate DBR-ed instances and schemas using different validaters. But Dare, if it is so, then what sucks is not DBR but validaters...Are they working so hard, or the spec is so sucked they are not willing to?
My thinking is that DBR is for local extension, while open content model is for outsiders. If an XSD schema was created by myself, then I can use DBR for my next schema. If an XSD schema was created by others, then I can't extend the schema unless they have defined xs:any in their schema.