Awesome to hear — our goal is to get to a point where you can copy/paste the design, but we totally recognize that it doesn't always get you to a full high fidelity mock up with the current limitations. So the main use case we've seen a lot of success with is ideating and validating different branches, quickly.
Oh that sounds very neat — definitely similar in nature! Documents and UI are both complex and can require a lot of iterations to get right