I might consider using this if there was an SDK for Node.js or another platform that I was into. That call is not really complicated, but having an SDK ready to go would make it a much easier decision to try this out.

Also ODT is the most flexible but if I could log in, pick a pre-existing HTML-based template from a library of common things like invoices or whatever, and edit it in my account with Aloha Editor or CK Editor or something, that might be just fine unless I needed special headers or something.

Then the API call could just give the name of the template.