I have in the last year become somewhat of a convert with regards to the more expensive cactus and succulent soil mixes you can buy at nurseries, I did not think I ever would, but during the pandemic last summer, I wanted to get my two soil components at the same place to minimize the need for me to be out and about, since most of the box stores do not sell pumice (I really do not get why you can get bags full or perlite there, but none of the big box stores here sell pumice), I put in a curbside order with a nearby nursery and they only carried the more fancy cactus and succulent mix (E. B. Stone brand if you want to look it up) in addition to the pumice that I really will not do without. I got two big bags of the fancy C&S soil and used one immediately while the other sat in my shade structure for the summer and did not get used till the fall.
I must say that when I grabbed that second bag I was pleasantly surprised, it is my experience with the cheaper ~$6-7 / 1.5 cu. ft. bags of C&S soil that if you let those sit out here, that in about a month of two when you open it, it has become one caked together hard block that needs a lot of work to break up - suggestive to me of the often forgotten ingredient in those mixes: really badly made compost (sewer sludge). The fancier mix ~3x as expensive was pretty much like I got the bag the day before I opened it rather than 3 months earlier. Though it has sand, it is a minor component and the other components are of relatively reasonable comparative size, whereas in those cheap bags you can find huge chunks of wood and what not. The intrinsic pumice and lava rock components are more significant meaning that I have to add less pumice to get to my desired ratio of pumice to other stuff.
So while it is probably not feasible for me, long term, to keep buying the more expensive stuff - just because I have so many plants to pot up and with bigger pots the amount of soil necessary per plant goes up quickly - but I can see why if you are using it for just a few plants - especially more expensive ones, it could be worth the investment and I will certainly keep buying it when I can.
