These are the word of Viv Billingham "Personally, I tend to prefer a smooth coated bitch and a rough coated dog for breeding, but the other way round would work out just as well. The reason I do this is that the dogs are better in themselves and tend to have more lining up ability and are less aggressive. As a bonus, you then get litters with both rough and smooth coated puppies. The hill or mountain shepherd often prefers a smooth - or bareskin - dog to its rougher brother because of the ice and snow in wintertime that can become balled up on to the feathering of a rough coated dog, thus making it more difficult or impossible for it to do it’s work. In severe conditions, rough coated dogs frequently have to be taken home and thawed out. Over the years its been many an hour we have sat in front of the kitchen fire with a hammer, breaking lumps of ice off our dog’s coats. "
I'm not so sure. I've definitely been out in freezing fog with Kip a number of times where his feathering has got completely frozen - all up his legs, his tail and even in his rough, and that was only being out for an hour or so. I'm not sure what he'd have been like if we'd have been out all day in it. I must admit I've never heard of it as being the reason for preferring smooths for working though and can see why your sceptical. I'll have to ask around - most of the working dogs in our area are smooth.
I am a little skeptical as my fiance and most of the shepherds in that area (Lammermuirs/East Lothian) have rough coated collies (with the odd smooth) and haven't had such a problem with snow balls and freezing fur that they would choose a bareskin over a coated dog for that reason.
I guessed that was the reason for your doubts But having seen it happen, I suppose it could be regional - some areas could be more prone to the types of condition that cause this (particularly freezing fog) than others? If so, in those regions, it may be more of a consideration than where it may only happen a couple of times a year, if ever?