If you edit JSON data using the JSON button on the Title Data page and save, any longer numbers will be altered without warning.
Example:
I have an object like this:
{"Guid":8787489952239432455}
When I open the JSON editor with the button on the right, change some other value elsewhere in my JSON object (I don't touch the Guid), after saving the object looks like this:
{"Guid":8787489952239433000}
This is unacceptable, altering data without warning defeats the entire purpose of using Title Data like this. This doesn't occur when using the field directly on the Title Data page, but most people will end up using the JSON editor you've provided, and have their data altered without their knowledge.
