My concern would be moisture getting in and causing sugar to harden into a brick. I say that because I forgot a bag of sugar in the van one winter-by the time I found it, it was a brick. I ended up busting it into large chunks to be dissolved in Kool-aid(too frugal to throw it out)

I think it depends on what kind of freezer you have. If you have one of those that are self-defrosting, I'd do a test first for a week or so. I find that the heat/freeze cycle of these typs of freezer cause any moisture in the bag to freeze, then thaw even with those vacuum seal kind of bags.