Not sure how things are in Chattanooga, but you will still have to exert yourself to climb hills, just way less than before. Also, REI lets you test drive these for free, so I would definitely try it out before buying!
350W motor, so you'll hit that 20mph limiter on the flats, but maybe won't sustain that up hill. It's better than a 250W motor, but not by a huge margin.