this thesis initiated in 1980 when bmw introduced the GS series. shaft final drive and "off-roading" will never work. one million plus GS models later that's been proven wrong. a belt final drive is light, very forgiving, extremely durable, and has alot of positives in actual applications. a ulysses with factory shielding and guards installed and ridden off-road has comparable reliability and longevity to that of a chain driven bike. here's some nice reading:
http://www.chuckhawks.com/motorcycle_drive_systems.htm