[Kanegasi]

All you need to save is the World of Warcraft/WTF and World of Warcraft/Interface folders. Copy those and put them somewhere safe, then drop the WTF folder you want to try in the original's place and install any extra addons this other player uses.

Once you're done trying this new layout, you can delete the Interface and WTF folders in the install then copy/paste the ones you saved back in to go back to your old layout. Do not delete the folders you saved elsewhere. It's also a good idea to regularly save the WTF folder just in case something happens. Sometimes addon settings get wiped on addon/game updates.

Just in case you don't know, the Interface folder contains all the addon code and the WTF folder is all of your settings, both for the game and what addons save.