I ended up a last minute judge on the Web We Want panel here at SmashingConf, and Adrian's pitch was the top pick by both audience and judges. This issue of content re-ordering is something I have been talking about for some years now, so anything browser DevTools can do to help would be excellent. I think this would be a great teaching tool as well, that I could use in workshops when teaching layout.
Run some tests or see which things are supported by different assistive tech. From the about page:
This is a community driven website that aims to help inform developers about what is accessibility supported. In order to conform to WCAG 2.0, you must write code in ways that are supported by assistive technologies (such as screen readers).
Our goal is not to tell you what you can or can not use, but to help you make informed decisions. For example, you may be able to use unsupported features in a way that does not negatively affect AT interaction.
After all, it’s our design thinking, our engineering, our planning, our work that’s made the Web what it is today. Collectively, we have quite literally designed and built some of these systems. When we work together—when we move together, what’s to stop us from redesigning these systems?
This is a wonderful piece, based on Ethan's talk of the same name. It's not about layout, but it is about what we all do, and I encourage you to read it.