Are geo-referenced plates a replacement for my aircraft's avionics?

No. Geo-referenced airport diagrams and plates can improve situational awareness on the ground, but are not certified for navigation. Pilots should always fly the aircraft using the aircraft's certified avionics. Never make course or altitude changes based on the data given by the device - always fly using your panel instrumentation. Additionally, personal electronic devices such as the iPad and iPhone can take attention away from the most important and demanding task: flying the airplane and arriving safely. Use personal electronic devices in an aircraft only when workload and conditions permit. Always enhance your iOS device's GPS performance by using an external, Apple-approved GPS accessory.