Some DataValue sublcasses use "hidden" or "secondary" values to augment the primary value, e.g. the globe URI in GlobeCoordinates or the upper- and lower bound in QuantityValues. Some of these may not be shown by the default formatter for that kind of data value.
However, in diffs, we need to see *all* data that may have changed. So, there should be a flag like "RAW_FORMAT" or some such passed via FormatterOptions causing the formatters to generate a more detailed output (in some cases, it may even be sensible to have a separate formatter class for this purpose).