I am using honda dio since last 2 years and experienced lots of tours. Long as well as local drives. The comfort level for back sit is something good but for driving sit is worst.
Even talking about milege, it is not satisfactory(~40km/ltr), since honda activa is giving more milege than honda dio upto(~50km/litr) . Pick up is normal. Engine is not well designed as compared to activa. In short, Honda Dio is not satisfactory for long drive.
Many other models like hero maestro, suzuki access and honda activa are best than Honda Dio.