Thanks for asking!
We are really sorry but we don’t offers any demo backend for testing to customer. As you have already used X, you most have fare knowledge about the the theme.
Here you can find a good article regarding the X and Pro:
The best way to get to know the Pro is to see the video tutorials of the Header/Footer Builder. Please check this page:
You will see a section dedicated to Pro which has good information regarding the Header/Footer builders.
We will be happy to answer any other questions you may have regarding Pro.