I'm running ozone on my 90 and preparing to add it to another tank. Using an Octopus reactor, generator, controller, and a Pinpoint ORP monitor as backup.
Tank clarity has always been pretty good so I can't comment on the ozones affect, however it has all but stopped film algae from forming on the glass. I went from scraping the glass every other day to maybe once a week and there really isn't much to remove when I do scrape. It also added a new defintion of nasty to the skimmate the Vertex Alpha pulls out. The Alpha always produced a foul smelling skim but it is now unbearable to be around when I clean the cup.
Other than the obvious downsides, it takes up a fair amount of room and is kind of noisy.