I'm not familiar w/ these brands of mixes, but mostly soil doesn't seem the best idea (like the 2/3 you're suggesting). I see you've collected others, so if it's working for you ... But pls. consider that in nature, these grow in crotches of tree branches, rather than soil, they're in leaf litter & debris, wastes & whatever else blows their way. So bark makes more sense that way, it's much lighter & more airy. (Indoors) I've mostly used soil w/ perlite myself thru the yrs. & have recently added a good portion of bark to my own holiday cacti. Am happy to report I've been able to keep an EC alive for a few months now in just bark & it's doing well. I've often struggled w/ECs 'til now. I've been using Repti Bark, from a pet store. Smaller (than Orchid bark mix), evenly sized pieces, nice. Perhaps try using that in place of your potting soil. So it'd be: bark, perlite & Cactus mix. Reviewing this old thread reminds me of Josh's point that bark mixes allow the copious watering these plants often get in nature.

I agree with petzold that the cuttings are probably still viable and with what was said about callusing. I don't understand the part about letting the pots soak for 2-3 days. That sounds like a recipe for a bog to me. I would pot the cuttings up in moist but not wet soil, place in a warm sunny locations, keep a close eye out on the soil to ensure that it doesn't dry out completely, and give the cuttings time to root. Most succulents are VERY EASY to root and I've had good luck with cuttings older than the ones you are working with. I guess, since this post is about a week old, that you have already gotten everything taken care of, but thought I'd post this anyway. I hope your cuttings are doing OK and maybe have plumped up just a little.

Sands that are beach (or mix with concrete) sands are very bad- they pack down. But some sands are so fine..they never pack. Those work great. I've mentioned Silver sands a few times that my mentor taught me years ago. I could never find it where I am. But when I had a sack? fantastic. Even if a plant died from frost? That potting soil was reusable after removing old roots. Some say play sand will work..but I tried that and it made the pot heavy. To give you an idea- Silver sands could spill from your hand like sand in an hourglass. Very fine. I was also told it has some use in minerals. Just try and find the stuff!

MIracle Gro soils are pretty much junk. Most container gardeners - and it really doesn't matter much about the type of plants: houseplants, annual containers, edibles, mixed shrubs and perennials and certainly any cacti and succulents - will avoid it like the plague. It is too heavily peat based, too water retentive and too prone to collapse and compaction due to overly fine particle size. Plant failures and rots are rampant with any MG soil! The best homemade houseplant soil is the 5-1-1 mix discussed extensively on the Container Gardening forum. It consists of 5 parts bark fines, 1 part peat or coir and 1 part perlite. It is durable and long lasting (no collapse/compaction), fast draining yet sufficiently moisture retentive. Cacti and succulents require an even faster draining, less water retentive soil and many growers prefer an all mineral "soil" or an almost all mineral soil - just perlite or pumice and granite grit and sometime coarse grained sand. Others will add some bark fines as well (eg. the 'gritty' mix). Most sources will strongly recommend omitting any vermiculite. While it is added to provide aeration initially, once it becomes fully saturated with water, it too will collapse and any draninage enhancement or aeration is lost and it becomes a soggy mess that impedes good drainage. This long post, written by a container gardening expert, is the longest running thread on Garden Web (first posted in 2002) which should say something about the info it offers. It's detailed and a serious read but will educate you thoroughly on why the planting medium for any container growing is so critical to the heath and longevity of any container planting. Link - Container Soils - Water Movement and Retention