The Bestem is a good case for road use. It doesn't work off-road unless you favor searching ditches to find where the pig shook off, but this can also be said for the much more expensive GIVI cases. The Bestem is a virtual copy of the GIVI, and the mount is interchangeable for some models.
It's not too much a PITA to mount. The mount plate is usable across a wide range of applications, and may, at most require a little light drilling.