I've observed a couple things while using the Rubbermaid's Configurations 4-to-8-foot Deluxe Custom Closet Kit.
Don't follow the provided directions and mount the vertical support bar 2 inches from the left side of your wall. Instead, I recommend that you center the horizontal support piece so that the shelving doesn't sit more at one side than it does at the other.
Also, the vertical brackets will indent your drywall when you mount them. This is due to the pressing of the backsides of the metal supports against your wall. If you decide to remove or re-position one of these beams, keep in mind that an imprint will be left behind if your walls are made of drywall.