Never used anything other than the <strong class='bbc'>Meguiar's No. 20[/b] at winter time, so I can't say. My results with the Meguiar's have been very good, especially when I apply two or three coats, but part of it depends on how many times you use a commercial car wash, if at all, how much salt gets used on the roads you drive, what the rest of your winter detailing habits are like, etc.
I'm certain that the <strong class='bbc'>Klasse & Zaino[/b] are equally good for winter durability. I think most polymer sealants are good for winter durability.