I agree that it should not use JSON. I think it would be better to use DER (or SDSER if streaming is needed) rather than XML or JSON, but that is just my opinio

I agree that it should not use JSON. I think it would be better to use DER (or SDSER if streaming is needed) rather than XML or JSON, but that is just my opinion. However, if the existing protocol already uses XML, then that is what it will be, but the new one perhaps would not use XML.