Users don't resize their browser — that's a developer behavior.
During conversations around responsive layouts, I've heard at least a dozen people say something like this. Certainly there is an element of truth to the statement, especially in the context of a single visit to a website, however it's not unusual for users to visit the sites they value many times over the course of a month, a week, or even a day.
Consider this article:
17% of US iPhone owners also own tablets.
54% of tablet owners use them to supplement a laptop or desktop computer.
Are you seeing the connection? We (and our users) browse the web with many uniquely sized devices and browsers. Our audience may not be clicking and dragging the corner of browser windows to see our awesome CSS transitions, but they are viewing the same websites at multiple resolutions.
So, here is my concern. When you do crazy stuff with your responsive layout — shifting things around just because you can — you're creating a barrier for the usability of your site. Even the most poorly designed interfaces can be learned, assuming there is consistency across uses.
To say it succinctly, familiarity breeds usability.
All of this has me thinking that these super-cool off-canvas layouts for small screens may be doing more harm than good.
Maybe we should use them to mimic the layout we opt to use at larger resolutions? Then our users could again learn to use our sites just once, no matter what resolution they happen to be browsing at.