I have read about quite a few "problems" with 800 GS's on this and other forums
I own an October 2008 model that has 43 000 km on the clock. I bought the bike with 30 000 km on the clock. It is an ex BMW Motorrad rental bike that has literally had the crap ridden out of it by a lot of different people including myself. It has never missed a service and I believe it has always run on good oil that has been changed every 5000 km.
The bike runs fantastically and the motor is silky smooth and super powerful, especially since I removed the cat and fitted a Leo Vince pipe (which is f&*(^g loud !)
A few things have been replaced under warranty by Atlantic Motorrad at no charge to me whatsoever, namely
- coolant pipes and clamps
- fuel pump and fuel level sender unit replaced at 34 000 km because of inaccurate fuel level display on instrument cluster
- new clutch at 40 000 km - plates were very worn and clutch was slipping
- new steering head bearings at 42 000 km - were rather tight and feeling notchy
Shane and his team sorted it out in the usual fantastic manner with no problems, excuses or bullshit whatsoever - I have had 17 bikes in the last 3 years (only 7 non BMW's including KTM, Yamaha and Kawasaki) and this is why I support the brand because of the excellent service and backup I receive, every time.
Every different model has its issues and in my experience BMW is only too happy to sort them out - quickly too. Engine failures are very rare in modern production engines but do happen - and most can be traced back to something that happened during operation (like sucking in dirt or bad oil, etc) and not poor manufacture or assembly or poor quality components
I really rate my 800GS but rate BMW (for their fantastic warranty and service) even better.