Thanks for asking.
As I said in my previous reply that you can't install X Theme demo in Pro Theme. Pro Theme does not has the concept of demo contents. Latest release we have introduces a brand new tool called Design cloud. More information and a sample can be found here:
However, you do have the option to first install X Theme and import the demo content of your choice from X > Validation > Demo Content. After that you can convert the same to Pro theme and continue using demo content. Once X Theme is converted to Pro, you can delete old X Theme files. More information on converting X to Pro can be found here:
Please let me know if that answers your question.