If you commute on your bike, I highly recommend a top case or at least a tail bag. Especially if you can filter through traffic (California, USA or Europe/Asia). Like I mentioned, the Givi WL901 is a very light weight case and complements the OEM side cases well. Again, I wouldn't recommend keeping anything of value in any of the cases unless you can park the bike in a secure location. Being rigid soft cases, all it takes is a decent pocket knife to slice them open.