Generally speaking, are commercial cactus mixes suitable as is for growing cacti and succulents? Would they benefit from the addition of other materials? The two mixes that I have are composed of fine sized material so I'm thinking of adding in something coarser in the form of Turface (calcined clay) and perlite. The mix is intended for Hatiora salicornioides and Rhipsalis baccifera.
Found the answer after some research. According to the informative article, Making Your Own Cactus Soil On-line Guide to the positive identification of Members of the Cactus Family: The article provides a guide to creating mixes for both desert and epiphytic cacti. (The plants in question are of the latter type.) I'll try using sphagnum moss instead of coir as that is what I have on hand.