I've planted some succulents in potting soil and others in cactus mix and they seem to do equally well (as long as I don't overwater and the pot has adequate drainage). Agree, the light is an important consideration.
@gjones Good idea. I love these little experiments. In my version the one on the right is cactus potting soil, the left is a soil free mixture with equal parts kitty litter, coconut coir, pebbles and bark chips
You're probably right. This is a very recent transplant so I'm sure it actually did lose a lot of its fine roots. That combined with using a super fast draining gritty mix makes for a thirsty plant I'm thinking!