We've been using a similar tool (https://github.com/BBC-News/wraith) for a little while now and it's transformed our way of working - 50 page layouts x 5 responsive breakpoints verified with a high degree of confidence in minutes on every build.

Well worth the effort to take the time to set up such a tool, particularly if you have a large UI test matrix - we couldn't possibly verify all the different page layouts and sizes before we introduced wraith