Hi,
Seems like this product wouldn't have any herbicide issues. There are a few more additions to the basic wonder soil besides the worm castings. I suppose some people might not want the moisture control polymers - but I think they would be helpful here in CA with our drought conditions. I came across this link:
http://christophererle.writersreside...pdf?1362585957
that gives more details on the various ingredients in their standard products (the coir, worm castings, bat guano, etc.) plus other ingredients they have in stock if you want to order a custom mix. (I imagine it would have to be a fairly large quantify for a custom mix).
I'm looking forward to trying it out. I should be getting some a little later in the week to try out (maybe with a little extra azomite) in my salad beds where I'm planning to grow most of my winter greens for juicing.
Anne