When people leave flex in barricade bars it actually makes it harder to gain entry than when they are flush with the frame. If their are bars on the windows I refuse to make entry until we rip every single one off. Keep in mind it only takes a few seconds to make entry through reinforcements with a k12 regardless, or we can just cut through the siding. These things deter more than just crimials, they will deter firefighters as well. (PLEASE don't put junipers or any conifer below your window, if your neighbor has a working fire they can light those things up, the heat pops your window, and bam - conflagration).
You want to know what works well for deterring criminals? Lots of lighting around your property and obvious cameras.