Not planning on using mine in the winter...took it out yesterday and literally never driven a car that's twitchier when there's a bit of slush on the roads!
The boot lid dampers seem to lose pressure when it gets cold and they are no longer able to hold the weight so the boot. I think it's just because of the age, if you fitted some new ones they will still hold it up during cold weather. Most still have the original damper fitted.
The standard trophy boot struts tend to go a bit crappy in winter and loose all their power as so the boot doesn't really tend to stay up properly! Mine had this issue before i bought it and the fool had stuck standard length 182 ones on resulting in a big scuff