I did not read all the posts in this thread. In fact, I only read the OP post.
Imo, you are being sold. All the best growers I know.....none of them use AN. The hydro stores I visit who personally grow, who could run any nutes they want, don't use AN. The two consultants I know, who are setting up these new dispensaries/grow spots (These are grow Gods) none of them use AN.
It's anecdotal, and limited to my area (New England), but that's a substantial number of knowledgable people, who don't use it. I do pretty well with GH, as do most of them.