If weight is your primary concern, it's hard to beat New Balance. Personally I wear these, Puma Klim. They're like Rock Climbing shoes but with a decent insole. They're lightweight and I've used them on a running machine but can't say they'd be comfortable on the open road. They're also stylish enough to use the rest of the time.

NB: They come in a myriad of colour combinations, not just the two available at the Puma Online Store.