How important is "autofill" for user experience?

Well I've got the obvious user-form. (Name, address etc).

I notice that google can autofill such a form, which is quite handy. However I also notice that in our case autofill isn't working. nothing is suggested and it stays empty.

Upon further research I learned that google won't autofill the forms if they have any so called "controlled" behaviour below it: an onchange event for example.

In our form we have onchange to "constantly" store the fields on the backend server (if there's a connection, and the last save happened over 400 ms ago). This prevents the need for a "save" button (it's still there for users as an anchor to give them the feeling they commit to the server, as well as a cancel button that restores the old field data).

So what would be better, have an traditional form with "save/commit", "cancel" etc buttons: which allow autofill to automate completion. Or have a managed form which apparently prevents google from autofilling, but allows automated saving (and just hope for google to work someday)?