A few weeks ago, I bought a small bag (10 lbs) of Aussie Gold mix and have just used it on my Black Jewel orchid. We'll see how it does in the next few weeks.
Just some tidbit of info... I read somewhere that diatomite can hold a lot of the salts from fertilizer and that it's not easy to flush it out with regular monthly water flushing. So keep that in mind.
For those who are interested in trying AG out and don't have a nearby nursery who carries it, you can order the mix through
http://www.aussie-gold.com .
Let us know if the mix works for you and for which plants.