I just got back from a 2400 mile tour with MCi tours around the Swiss alps, Dolomites and the Grossglockner national pass. There were 25 bikes on the tour and the problems were as follows:-
Honda Pan European 1300.
Rear brake locked on. The fault was caused by the ABS unit which had failed. Cost £2000 to fix
Honda Blackbird
Alternator failed. Fixed in Switzerland for a mere £500.
Ducati 999S
Clutch started playing up and needed bleeding.
Ducati 748
Developed a death rattle from the engine and was shipped home by the breakdown recovery people.
Of the six BMW's on the trip there were no mechanical issues, though the guy on the R1200S crashed it and it was too badly damaged to be repaired locally. Fortunately he was ok with no broken bones.