Hair sheep do not need their tails docked because they are shorter and as their tails are not covered in wool, the feces do not stick to them. Typically wool sheep have their tails docked because manure stuck in the tail attract flies.
There are also many claims that hair sheep experience fewer problems with internal parasites. I will say that keds are much less of a problem with hair sheep.
We find having a hair sheep ram to be the best for our breeding program, which includes larger wool sheep ewes as well as some hair sheep ewes. The hair sheep ram means smaller lambs at birth, which translates to fewer lambing problems for the ewe. I would not suggest breeding a hair sheep ewe to a larger wool breed ram. The hair x wool sheep have an odd sort of coat that sheds partially.
We live in Canada, and have cold weather in the winters. They hair sheep grow thicker coats in the winter, but should have winter protection (we keep ours in an unheated barn at night in the winter). This is not so much of an issue really as we lamb in the winter so all our ewes are in the barn at night regardless of breed. As you would expect, they are very tolerant of hot weather.
I would especially encourage anyone who wants to have sheep as pets, for meat, or for pasture control to consider hair sheep.
We have owned Barbado hair sheep as pictured above, Dorper, and Katahdin, which I am sure you will read about it other blog posts here!