I think a belt will outlast a chain. Harley uses a Gates belt, same kind of belt bikes are using and the size of belt used is actually more robust on bicycles when taking into account power and weight of a bike and the motorcycle. The H-D belt lasts 50 to 100 thousand miles.
I don't own a bicycle with a belt and I don't feel the need to own one, but I do own a Harley with a belt. Clean, quiet and trouble free. Time isn't the factor as much as miles, power applied and terrain where ridden. A chain can last a long time depending on application. Using a Park Tool chain measuring tool shows the stretch, and a stretched chain starts to wear cogs and chainrings. You don't get that with a belt for a very long time.
Nothing wrong with either setup.