Different areas around the country/world have differing needs in soil. The trick is finding what will work in that very harsh Texas summer sun.
I don't think any of the hardy type sedum or sempervivum will handle full sun in that type of weather.
I do agree with Karen about the fast/sharp draining soils. I can get a great Cactus Potting Mix here, but not all cactus potting mixes are created equal. If you find one that has a fair amount of sand and pumice, with some forest product mixed in, that would be great.
If not, get something like Miracle Grow Potting Mix, not Potting Soil, and no moisture control beads added. Then add sand, pumice or chicken grits to it.
