I finally just gave up on steam irons. I went on a similiar search several years ago and do believe that using/leaving water in any iron is a recipe for future failure. Therefore I bought a Rowenta 1600 in 2014 and have never put a drop of water in it. It is still going strong. I use one of those misting spray bottles and a wool pressing mat and that has been my solution to this ongoing search for a perfect iron.
I wish you much success. And please post what you finally find.