Shnatsel, a member of the Elementary OS team, has created Glimpse, an application that lets you test unstable applications without interfering with the stable versions:
You open Glimpse, click “Update sandbox”, and the latest version of the player arrives in a few minutes, not hours. And if you find that all the music files in the sandbox are broken, you think “thanks to Glimpse, my files are safe,” click the “Purge sandbox files” button, and your original music is available in the sandbox again.
Glimpse supports elementary OS and Ubuntu for now, but it may support other Linux distributions in the future.
Glimpse has not been accepted as an elementary application yet because the UI is not exactly pretty. But you can try it out already - read all about it @ Shnatsel's blog post: We've Just Revolutionized Alpha Testing.
P.s.: the Glimpse Ubuntu profile ("glimpse-profile-ubuntu") has not been built in the PPA yet so skip its installation for now. It should be available in a few hours.