Thanks for the comment @account42 Agreed that a really-great responsive site is one where specific viewport dimensions don't matter. One thing we've run into (and want to test for) is users mentioning they're using a specific device and having issues.

In those cases, it's helpful for us to really quickly choose from a list the device, and view the site. That way, we don't need to know the exact dimensions of the device, and can also test a possible fix for that device against other viewports.