Not sure if we are referring to 'storage' or 'driving' in the colder months here?
If it's storage, it's always roof up AND dust cover IN the garage. I've also considered one of those 'bubble' things to keep the moisture at bay. Maximum protection of the interior!
If its driving we're talking about then it is always 'lid off' as Mrs T refers to it - usually with side screens on the old 4/4, but the Roadster has side and rear wind deflectors so we're going to try no side screens... even in the middle of winter!
We have a tradition of a new year's day, lid off, drive to blow the cobwebs away, having made sure we are not over the legal limit!
The soft top is only for use in storms that have been given a name (drove the Roadster away from the Dealership in the middle of Storm Amy recently... I did think for a second to take the top down, but relented!).
REMEMBER: When it comes to top down motoring, there is no such thing as impossible weather, just inappropriate clothing! Get a sheepskin jacket and lots of microfibre cloths!