Really cool idea, but a few key features would turn this into something I could use every day:
1) the ability to switch the container of an open tab. I frequently open tabs, then have to close them and open a new container tab because I forgot to open the container tab first.
2) a way to open certain bookmarks (or pinboard links) in a particular container. I'd like to be able to log in to google drive in two accounts in two containers, and when I open the bookmark for Corporate Google Drive, I'd like it to open in my Work container.