KTM in the garage... totally different ride... 
Interested to hear an expert opinion. What made you choose the BMW? Or was it a good opportunity that presented itself? (I hope this post does not invite brand bashers).
I have never been totally attached to a particular brand... the garage at home has a Honda, a KLR, the 640, and now the BMW too... they are all very different and satisfy certain needs and are perfect for particular applications and wallet requirements... I believe that EVERY bike is a compromise... so whatever you are doing, ascertain the things you can do without, and thereby ascertain the right bike for the application.
The 800 is a stunning bike, but I would not not want to throw it up a chasm, potentially destroying it, rather use something designed for that, in the same way, running 800 tar km's on the 640 would fall into the category of "distinctly unpleasant".
On that note however, I will say that this bike is a massive improvement on the 800 I owned before, and I find I am pushing boundaries on this bike already... it is very capable and I'm getting back into using a computer...