Since Z-Wave is RF based, isn there an issue with range?
No. Each Z-Wave module (like a plug-in dimmer module, or wall switch) can act as a RF repeater. When a controller sends a command to a device, it may route the command through other modules in your home to get the command to its destination. Range from the controller to a single module is rated at 100 ft. Commands will route through a maximum of 4 devices. This gives the system a max range of 400 ft. Routing is done automatically and the user does not need to be aware of it.