I would note that the weight difference Paul Rivers mentions is dependent on how an IGH bike is equipped versus the road bike.

The Civia Hyland includes a hub dynamo, fenders, rear rack, dynamo headlight and chain guard that are not found on road bikes. Also wider and likelier heavier tires than on most road bikes. This does affect weight comparisons. I would expect that the weight differential between identical frames set up with a 8, 9 or 14 speed IGH and a derailleur road bike would be in the neighborhood of 2 pounds more for the IGH bike. I posted asking about this some time ago, asking if anyone had actual measured differences, with no replies.

The road bike also typically places the rider in a more aerodynamic riding position. As aero drag is one of the largest influences on bicycle speed this can have a major effect on cruising speed.