I used to own one of those and rode LD on the slab and took it on tough, singletrack and doubeltrack trail (i.e, Devil's Punchbowl). I spent a ton of money hanging bits and bobs on it trying to make it the bike it was advertised to be.
After doing all my own maintenance, I came to the conclusion that Marketing degrees are prized more than Engineering degrees at BMW these days.
In the end, I gave up and just bought another bike which was truly designed / engineered / manufactured to do exactly what the brochures claimed it would do.
Not trying to rain on your parade....just seems like you're awfully fixated on one specific bike and having been down that road, I thought you might take advantage of my experience.
Best of luck with the hunt and I hope what you're after hits the spot.
Alright, this is just fancy car camping, people. Move along, move along.