Very interesting article from Mozilla Accessibility Engineer, and vision-impaired user, +Marco Zehe
about some recent discussions around informing sites about the presence of assisted technology running in a user's web session.
I'll begin by saying that I am nowhere near as good about developing with accessibility in mind as I should be. However, I tend to agree with Marco's points he raises. Trying to maintain a 'core' application and an 'accessible' application is something that, in practice, developers are unlikely to do. Which will just lead to the 'accessible' version falling behind and lacking functionality that the 'core' part has.
Accessibility is work, and having known a fair number of VI users from online communities, I have some small understanding of the difficulty they can face trying to use the modern web. But I sincerely suspect that Accessible UX Design is likely to result in better design for all users, whether they're vision- or mobility-impaired, or even for the unimpaired user. And it's less work to make a single product accessible than to maintain two different products.