I know of a gentleman who drove his Boxster S (06) thru canadian winters with no problems, that same guy just purchased an 2010 911 C4 and plans on driving it as well all year long.
My question is, in Canada cars start developing rust spots in average of 4 years of age if you drive them all year long, because of the salt n calcium on the roads, does that happen to Porsches as well, have you tested it? 95% of Porsche owners put em away for winter here btw.