Alacowman,
The Luing sheds out in warmer weather. My concern about adaptability is because no one has tried them in Texas yet. If some one is looking for a small breed with good maternal, calving ease and longevity they may work in a cross breeding situation in Texas particularly with the American breeds as they are easy breeders and marble very well.
By the way the Murray Grey and Tarentaise are known for their adaptability to hot conditions. The Murray Grey was developed on the Australian range and the Tarentaise is the go to breed in North Africa for fertility improvement with heat resistance. Do you see a place for breeds with these traits in Texas?