Is it critical to have tonneau cover with a bed rack?

Am I over thinking this? I want to put a RTT on my bed rack. As far as I know the KBvoodoo is the only one that allows you to still keep the factory tonneau. I don't care about not being able to open it. I am more concerned about safety of stuff in the bed. Do the other racks like RCI keep big stuff from being taken out? Has anyone done any modifications other than chaining stuff like mounted hi lifts? I am sure there are times when I will not have the tonneau on and any rack would do fine.

 

A tonneau is a great way to keep your stuff out of sight of thieves. A bed rack alone offers no security.