Some collie breeders will tell you that smooths shed more....but some collie breeders feed Pedigree.
Anyway, a good friend of mine has had three smooths, currently has two. She grooms collies for extra money, and most of her clients have roughs. If fed high quality food, the smooths do not shed as much. Hers are fed Solid Gold Wolf Pup, and get Showstopper and brewers yeast supplements. Honestly though, if a rough is kept groomed, bathed and brushed you will not see so much in the way of "tumbleweeds" (ha ha, I love that expression).
What she hates about roughs is that sometimes they get poo stuck in their pants if they have loose stools, and they usually get a little poo stuck on their bottoms which she ends up having to wash off. The smooths don't have that problem. She has told me that some day she would like to have a rough. She just hasn't found the right one yet.