I'm happy that you already had an issue open for accessibility. Thanks!

This demo app isn't bad. The biggest problem I've found so far is that a screen reader user doesn't hear anything when a client-side page load happens. This is a common problem with SPAs, and there isn't a great solution for it. The best you can do right now is use an off-screen ARIA live region to announce something like "navigated to [page name]". Sometime though I'd like to work with the web standards community to standardize a better solution.