I saw from a post in one of Doc Bud's high brix threads that you were concerned about Azomite toxicity. I reviewed the literature and came to the same conclusion you must have, that it seems safe enough. I've now got some on order and will decide on the addition based on it's specs, gut feel, and Doc Bud's comment that he used to add a pinch in the amount of it you could pick up with chopsticks. I'm only mixing for a total of 10 gal.
To me, trace elements are like vitamins, to be used in very, very small quantities. A quick look at the ingredients told me it has elements in it that OC+ doesn't, and since am not using soil or stuff like OH Micro, I'm going with it for its breadth of mineral composition.
Cheers