The Af-Twin is an ace bike. However, when I got mine.. the first thing I did was to go and get the seat cutdown. It is a bigmans bike. And it is a heavy bike. I do love mine to bits and would love another one to bring it up to date (with KTM forks, digi dash, etc etc).
I think you may have a good market in the future, when the bike becomes quite rare, there are still quite a few about (unless you have some Marathon ones from the Dakar). I would say maybe have a selection of bikes in your stable.. for example.. I would love to have a go on a KTM990 for a week or so then return it before I had to pay for the repairs. I would also love to have a go on a R100GSPD.. if I did it I think I'd have a selection of good touring bikes and some classics. If I was a BMW owner maybe I would fancy a go on an Af-Twin or a KTM etc etc...
Also I bloody love Switzerland... it's my life aim to move there.. lol gotta ride the Africa Twin to Australia first though... can't wait.... ow Ich also muss sort out mein Deutsch... Es ist shit und ich bin not sure how I'd get ein Job in Engineering nur mit English :)
All the best