Aside from confused scrolling and screen reader problems (and I'm not downplaying these issues, it's just that I've already discussed them at length), are there any concrete accessibility and usability issues associated with iframes?
So the first document that I use for this kind of question is WCAG 2.0 (about frames)
As the document say:
Using an iframe it's possible but you have to face a different structure of the site (It's no more one entity but a composition of more entities). What are the possible usability issues?
To prevent this issues you can:
From a purely usability standpoint, having a div with overflow:scroll looks the same as an iframe. With that said, there are alot of places things could go wrong:
But as an example: I made a salesforce.com app. The whole system forces you to use an iframe. We worked hard on the details and the design was seamless for the user. Never scrollbars, etc. So it can be done.