Hi Igor,
The BasedOn feature won't work across domains that way. However, you should be able to open each step of the new suite, change the URLs and update the step. That should answer your needs. In any case, a review on the BasedOn feature is already on our backlog.
The import/export feature is/should be the right approach for what you're trying to do and it should work just fine the way you described. Nevertheless, we'll review it to make sure it's working properly and get back to you soon.
The TestFramework is under a big refactoring, which started a few releases ago. Please bear with us as we work on improving it and its users experience and thanks for your suggestions!
Thanks,
The TestFramework team