I know about salt from the sea here as I am only about 800 metres from the English Channel. I have had aluminium outside light fittings corrode because of it. However I have had my Davis VP1 now for nearly 3 years and so far my only problem was corrosion on the ISS circuit board whilst under guarantee. This I think was caused because I had not ensured my ISS cover was properly seated/sealed against the elements. So its not all doom & gloom, but as with all this YMMV 
Stuart