I went back and forth with the idea of adding UV to my system. Hydro Innovations gave some great pro's for using UV but I ended not buying one because of the potential to kill the "good" as well as the "bad".
I have three tangs in my system. I feed frozen food and nori soaked with garlic one/twice a week and that keeps the ich monster at bay. I have never had an outbreak, though when the tangs first were put in the system they all got a small infection of ich. Nothing major, just a couple spots here and there.
I figure ich is inherent in my system, just like cyano will always be (it's always waiting for the right opportunity to flourish). If I can naturally keep it at bay, then I will aim to do that instead of adding additional equipment to remedy. Plus with all the frag trading and water from other systems, I'd be crazy to think I can keep an entirely sterile tank with no ich or anything else in the water. If I can keep the conditions that it favors most at a minimum, then I don't have a problem anymore. Just my 2 cents.
-Ty