Nice article! I do have a few tips actually.
Priority inbox lets you put "important" mail at the top, but you can still see "everything else" right below. It's also very customizable. Even if you're scared that you'll miss something that we didn't mark as important, you can use PI to help prioritize, and still read through both the "important" and "unimportant" inboxes.
Another of my favorite tips is using keyboard shortcuts, it's amazing how much these can speed up your "email slaying." In particular I frequently use keyboard shortcuts to archive & move to the next message, and to add an email to my Tasks list.
Finally, Gmail engineer
+Balázs Szabó just recently wrote a blog post on his own productivity flow, you might find it interesting!
https://plus.google.com/113390745456243234557/posts/CckYh1UM7oS
Nice article! I do have a few tips actually.