This 4 bike is better than other styles I have used. Better than roof racks, better than the pole type. Main advantage is quick load and unload, and access to the back of the van when loaded.
It is quick and easy to load the bikes.
The add on makes the whole unit a little on the heavy side. I think my wife could not install it or lower it to get into the back when the bikes are on.
If you have a friend to help install and lower the rack it is really fast.
If someone determined wanted to steal the add-on with the back two bikes locked on they could, given time. But they would be moving slow carrying it all and have to cut the bikes off some how. Probably not worth it for them.