One consideration might be schemaless JSON versus schema-driven XML. It is a matter of convention, since XML can be written without a schema and JSON with a schema, but the conventions put pressure on XML to have a schema and JSON to not have one. The unique particle constraint, for example, would reduce the number of valid XML possibilities if the XML has a schema. 

Another limitation which might be different between XML and JSON is the evolution of the document over time. Changes to the XML over time, especially if there is a need for backwards or forwards compatibility, might be differently constrained compared to JSON. Cardinality is a typical change area and neither are good with this but if a schema is included in the XML case it might increase the divergence from JSON capabilities. Growth and extension points: neither are great here either. XML schemas guide designers to build in extension points so that you can have a complex type which allows additional elements to be added over time. A key differentiator is attributes in XML which cannot be extended. XML which includes attributes can only extend an attribute to turn it from leaf to branch if it is changed from attribute to element so that it can have children.