I have the vario on my 2011GS if the alloy boxes mount different than the vario I would go with them. Seems their are some instances where the vario boxes can depart the bike at speed or rough roads. I have installed the BMW enduro kit to prevent this from occurring $30 US from dealer, ouch, 2 screws 2 nuts 2spacers and a couple of washers and a nice 60 page installion manual in six languages.
Look up the installion guide on line you can duplicate the parts for a couple dollars at your local hardware store
You will still want to key your case to your new bike will your dealer do it for free?