Could there be some common factor that stresses the cameras more than normal, in such a way that is more harmful to Canon gear? Did the particpants ship their gear in the unpressurised hold of an aircraft? In which case maybe pressure changes stressed the seals? Or were there large temperature differences between the cabins and the outside? I'm guessing, but Canon users on forums get really twitchy when these trips are mentioned. It is bad publicity for Canon, that is for sure.
From what we hear, conditions during that trip were
much milder than what many of us experience on a regular basis in other locations. The key probably lies in the mix of sea wind deposited salt and condensation.
Canon never claimed that the 5DII was fully weatherproof, did them? They just claimed that the sealing had been re-inforced. A body that is not fully weatherproof is not weatherproof. Light rain is not an issue because it doesn't hit many parts of the body. On the other hand condensation will show up everywhere, and is going to dilute salt deposited by sea winds, and this salty water has the potential to enter through these non protected areas and cause corrosion.
On the other hand Nikon clearly insisted on the weather resistance of the D300, D700, D3 and D3x. Is there more to this story than the intended usage of these respective cameras? Canon is still selling the 1ds3 for a reason, and that reason is that they designed
and validated the camera in various demanding conditions. Aren't the 5DII users expecting that kind of performance not being a bit un-realistic about their expectations?
Cheers,
Bernard