I've built a BulkAttributeValidatorWithMapping, takes external configuration file like SchemaMapper, allows logical testing like Tester (including NOT), can group tests together (eg "Attribute A is a number, or Attribute A is blank"; or... "Attribute A is ABC or Attribute B is DEF"), and custom error messages can be entered (each failed test is concatenated onto an error string). It works with un-exposed attributes (designed to work with an upstream SchemaMapper). May take a while to run as it checks each feature against each validation rule.
If anyone is still following this thread and is interested, I'd appreciate any feedback.