It's easy to auto save small things. And it's easy to do in software on your computer. The hard part is doing it in a web browser in a non invasive fashion behind the scenes so a user doesnt notice it and it doesnt slow down what they are working on.
Our listing form has a large amount of data to transfer which presents more of a challenge.
I'll see if there is something we can do. It would be interesting to see this operate on a site that collects a lot of data like we do on the listing form. If you know of a site let me know.