It's a little bit tricky with the weathersealing... I always thought my EOS1n is quite a good rain-keeper until last week where it failed in a normal summerrain. The 100L was ok but the cam was wet under the top-plate which kept the whole thing from working. There was even some water nearby the filmentry but it didn't came full to the inside. The batteries got destroyed, too.
After baking it in the oven @50°C (for ca. 20 hours) the body worked again but hey I don't trust it anymore. The thing with the weathersealing on lenses is not to full destroy them, they work for 99.99% of the time. But they will get fog or fungus after a few years... that's the problem fo sealing. If I hear the advertisement for the 5D Mark III Bodies which Canon claimed to be "as weathersealed as the old EOS1n" I don't have any good feelings with it
Damn, If I only could effort the 1DX ;D