Have also heard uniformly positive/glowing reviews of 599 dynamics/durability from guys who have driven 599 regularly (though at a mere <15K km/yr pace; lots of mtn twisties/urban commuting, but no derestricted AB)...
Suspect your impressions of 20K+ km/yr driving in Germany, esp AB, will prob be among the best stress tests of any privately-owned 599 on planet....
Agree...most software updates will be incorporated at svc visits, but I would think any changes to hardware (e.g., faster computer chips, different chassis viscoelastics, different CCB materials, etc) will be subtle changes that can't be easily updated...