Ha, Rich Dad Poor Dad is sitting on the bookshelf. If I had more rocks, it too would have been used
Regarding Zoa's...
For starters, I'm not convinced that zoa's do better under the "dirty water" theory. Check out Victor's display tank at WWC or one of JF videos on his website. In both systems, they have a balanced tank of SPS, Chalices, and Zoa's.
Here's my theory...
I'm no expert and this is solely based on observation and past experiences.
Prior to introducing SPS, my zoa's were doing fantastic. I've been running LED's for quite some time and I've always had good success. With that said, in my honest opinion LED's (no matter the brand) require much more dedication. Acclimation, observation, and finding that sweet spot is absolutely imperative and much more difficult. I find that this really isn't the case with MH and T5. Such with all corals, you still have to acclimate, but after that you're good to go. The reason for this, is controllability. Which leads me to my next point.
Once I added SPS, I gradually increased the flow and intensity. Even thou the spectrum was the same, and all that had changed was the intensity, some of my zoa's became smaller, shriveled and looked like crap as you mentioned above. To resurrect and remedy the problem, I found myself starting from the beginning...acclimate, observe, and ultimately find that sweet spot. Water quality always stayed the same. After time and trial and error, I was finally able to succeed. After the light/flow change, some zoa's continued to do fine, and others didn't. My UC was one of those.
So to summarize, I don't believe it's an issue of keeping Zoa's and SPS together, but more about finding that sweet spot for the zoa's to coexist in the same tank. I'm not sure if you're currently running LED's, but I do know that you have your Radions on standby, therefore the info above might help once you start adding corals.