I had WP Supersized working on a site as well as a slider on the home page (Using Orbit which comes built-in with Zurb's Foundation) and displaying a photo gallery and using Jetpack's carousel.
WP Supersized works and gives me great background images, but stops the slider on the home page from sliding automcatically.
WP Supersized also affects how the carousel behaves on Firefox. The comments appear on top of the photo.
Once WP Supersized deactivated everything went back to normal and both Orbit and Jetpack at super happy.