Hey snowjunky, I don't have an answer to your main question.
But with regards to Eugenias growing in AZ soil: While most of my Eugenias are on mounds with lots of compost, I have two in the unamended ground directly - E. uniflora (Pitanga) and E. neonitida (Pitangatuba). The Surinam cherries do great in the AZ soil like you mention (if they are given a bit of noon+afternoon shade), but I also find that the Star Cherry does as well. I have another Star Cherry growing in compost that is growing better (fuller and greener) but I have 2 in the AZ soil that are doing very well and producing fruit. Also the Star Cherry takes the heat and sun better than the Surinam. So for Eugenias that are best adapated to our climate and soil, I would have to go with the E. neonitida. The only downside is that it is slower growing than E. uniflora.