I don't think I followed any of these for my side project (www.diff.so) because, well, it's a side project! It's a prototype, something I did for fun. This is a great list of things to do before I expect someone to use it seriously, not a pre-launch checklist.

To go a bit off-topic, I actually tried to follow the "don't use color alone to provide information" for the static diff on diff.so/about, but I couldn't find a way to get ChromeVox to read text on one side of the diff any differently than text on the other. I'd be really interested in any advice on that - it seems like some screenreader users could use something a little more user-friendly than emacs.