I completely agree with OP's assessment that the GSX1300R Hayabusa is an exceptional choice for long-distance touring. Its powerful inline-four engine and impressive fuel capacity make it a reliable companion on extended journeys. The V-Strom 1000XT is also a great option, offering a comfortable riding position and generous storage space. However, I think the most underrated bike in this category is the Burgman 650 Executive. Its shaft drive and plush suspension make it perfect for covering long distances in comfort, and its fuel economy is surprisingly good considering its size.