D700/D800 are weather sealed to the same level as Nikon's D3 and D4 - i.e., the best available.
5D2 has some improvements over the 5D, but is in no way as sealed as the 1D series (which has similar sealing to the film 1V body, which was Canon's toughest film camera). The 7D is a bit better, but still not up there.
I've personally had several 5D2s fail on me due to bad weather, and have seen other people's 5D2s and 7Ds fail during expeditions. The only time I've seen a Nikon D300, D700, D300s, D3, D3s or D3x body fail was then someone dropped a D300s into a hot spring... and, even then, it worked fine after it was dried out for a few days, and the images on the memory cards were still intact.
Good to know. Thanks.
Switching now




