Thanks for asking.
You can upgrade to Pro but we suggest you to first update X Theme and Cornerstone to the latest version. Along with that I suggest you to fist test the upgrade process on a staging server. In case you hit any road block, together we can troubleshoot the problem without affecting the live website.
That being said I suggest you to first take a look at our Theme Upgrade and X to Pro conversion guide for more information:
Let us know how it goes.