Tandems will ride smoother and be easier on your cargo. As the front tire hits a bump or a hole, the other one will go up or down to partly compensate.
You'll have to check your state laws for what's required for brakes. More and more states are going to requiring a device to set the brakes if it comes loose from the truck. That in itself is easy to do but it does require a battery on the trailer, which requires the wiring on the truck to keep it charged.
