i have a dowco cover and i keep my bike outdoors during the season up to thanksgiving. but id suggest finding a spot for it..I worry to much when its windy out, so in the winter it would drive me nuts...
One thing I do hate about having the bike outside under a cover in the city is the birds....so much bird crap on my cover. Winter time always brings lots of birds crapping on my car and covers....
I try to wash the cover once every two weeks because there are atleast 10-15 crap spots on it.