what folks seem to miss most in our Soil FAQ is that OUR SOIL DOESN'T MATTER 
it isn't about being able to find decomposed granite. most people can't. some that can, only find the chunkier, unusable stuff, and then they think i am some kind of lunkhead...
there is no brand name for it, but it is not important. what IS important is to get out there and FIND YOUR OWN LOCAL OPTIONS. call around, sure, but not just for decomposed granite, call around for "soil", find some good possibilities, and then go try it out.
we went through half a dozen different types before settling on what we thought worked best. and the DG is just that, a SETTLED FOR soil. it does perhaps 85% of what i would like it to do. but for our setup, our tonnage, and our needs, it was the best choice we had.
take a few five gallon buckets, and go get some different types of soil. setup some 10 gallon or 20 gallon tanks, just like you would for a baby monitor, with hides, basking stacks, water bowl, lids, ventilation, etc, and work with it for a couple of weeks. get your temps right, and see how it responds. dig in it, burrow in it, just spend time with it.
some soils will be crap in 6 hours, you will know right away they are bad. others will work great when wet or moist, and then turn to concrete overnight. just mess with different stuff, and while you are learning about soil, you will find one that works.
if you completely fail at finding a nice local soil, then try the Home Depot mix from the FAQ. it works pretty well, and while using it, you can start to understand what it is that you are looking for, the good and the bad.
perhaps i will add an addendum to the soil FAQ, because so many folks get stuck on the "DG" and really miss the true point, and that is to explore your local resources, and find something accessible to you that works well. there are plenty of choices out there, folks just need to learn to recognize them 
best of luck!
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robyn@proexotics.com
Pro Exotics Reptiles