> "Client-side rending (such as Angular/Backbone/etc) really shine when you need a web application (not web site)."
This, 1000x over. I have static landing pages and about pages for search engines, but the app itself is a single page Angular app. The data does not have to be indexed.
Exactly. And if you're going to use it for a content-driven site, don't use it to serve up content, use it to make a nicer UI around the content. And if you do use it to serve content, make sure that content is also accessible through a direct URL of its own, so you can show that to Google.
Though Google is cheating here, of course. They use plenty of JS frameworks to serve content, yet those Google+ posts do show up in my search results. Though every G+ post does have its own URL, so I guess that's the way to do it.
This, 1000x over. I have static landing pages and about pages for search engines, but the app itself is a single page Angular app. The data does not have to be indexed.