My winters are nothing like yours in Canada. We don't get too much snow. I might get a little ice on the pool but it doesn't stick around more than a few days before it melts. I drop the water below the skimmer and below the return and don't have to worry about it overflowing.

I just thought of another reason I quit using the cover. Leaves that fell on top of the cover that were then rained on caused green, nasty decomposed leaves to accumulate on the top of the cover. Sometimes I would have to use a sump pump to drain part of the water from the top of the cover. It was also hard to get the cover off without having that nasty green water spill into the pool.