The current problems we're having are DS covering up adjacent text with their input box. You can specify a starting width, which helps sometimes. But they have a minimum font size of 9pt and minimum input box height of 22px and we often need to go smaller.
Why is this important to us? We're filling in official state forms and we cannot change them in any noticeable way to give their input box more room. Some states have crammed everything together and we have to work around their poor design as best we can.
That DS provides traceability, viewing history, and cryptographic signatures is nice for us, and may help one day in case of a lawsuit. It's not a must-have for us, but likely was important for them given they originated in the real-estate document area (lots of disputes there, I'm guessing)
What could help us is making the input box translucent, or hiding it until the user navigates to it (perhaps leave a small marker so they know they have to provide a value there).
So far as the templating, we've got that solved with Fluent (née Autotag). Most of their competitors are doing simple word replacement (mail-merge) but they allow us to add logic like if-else and select-case to our templates. You should look into doing that too.
Sounds interesting! Those tools preserve the original document's style — do the documents you sign follow a specific legal format or design that needs to be maintained?
Yes - we make every effort to get them as close as humanly possible - spending lots of hours matching fonts, images/watermarks, layout and even spelling & grammar errors. We don't want someone at the state office to reject a submitted form because it doesn't "look right". At our volume, that would be bad.