I'd argue an open matte, non-OAR ratio is nothing more than a side show and not acceptable for a preservation project, unless it is re-matted to the proper theatrical ratio. Most likely, visual effect shots would be cropped unless they did the effects open matte as well.
One place this could come in handy is if a 2.20:1 70mm ratio wanted to be used, and again, we re-create the mattes. That of course assumes that nothing is ever cropped.