Let me elaborate more on my position when it comes to ozone (supplemental oxidizer) and chlorine (primary oxidizer and and sanitizer) in a hot tub. I have no dog in this fight so I really don't care much either way what people choose to do, but there are details here worth discussing and acknowledging so that users can make informed decisions.
The first point is this - chemistry in a recreational water body like a hot tub is very complicated and does not lend itself well to simplifications. This is true in pools as well but hot tubs are doubly more complex because they are very small water volumes with very high bather loads, they are constantly heated to high temperatures, and the human body emits and sheds all kinds of nasty chemical compounds. If anyone has every given a child (or two or three or four) a bath, one notices right away that the pristine water the tub was filled with quickly becomes a cloudy and smelly soup of human waste. Hot tubs are only a bit bigger and typically hold multiple human bodies at perspiration producing temperatures for soak times much longer than the typical bath. This loads the water up with salt, urine (urea), creatinine, oils, proteins and, in some cases, beer (both virgin and .... processed, shall we say).
The second point - chlorine and ozone are both powerful oxidizers and sanitizers (although one doesn't typically use ozone for sanitation). They not only react with one another (neutralizing each other) but they also attack organic compounds in the water. These organic + oxidizer reactions are very complicated and there are cross reactions between the two oxidizers. You can't just simply say that because one oxidizer does one thing, the other oxidizer will sit back and wait....reactions happen simultaneously and with varying complexity. Most of these reactions will result in what you want them to do - oxidize complex, organic bather waste into simpler compounds. However, some of these smaller, simpler compounds will then go on to react with the chlorine further potentially leading to end-products (trihalomethane and disinfection by-products) that can no longer be oxidized and are toxic in nature.
The third point - not all combined chlorine (CC) compounds are created equal and some are definitely "more equal than others" (that's an Animal Farm reference for anyone who ever read the book...). Simple, inorganic CC compounds like monochloramine and dichloramine can be further oxidized by chlorine and ozone to chloride salts, nitrogen gas and nitrates. However, organic chloramine compounds, like chloroform and chlorourea, can not be broken down much further by chlorine (even at shock levels) and ozone has trouble with more complex organic chloramines. This is subject of "breakpoint chlorination" and what gives rise to the total chlorine versus free chlorine curve where one sees that the TC stops rising and eventually falls when the FC gets high enough. But there is sometimes a "floor value" of TC which increasing FC never reduces and that is the non-reactive chloramines that are formed. Ozone can reduce that floor value a little bit but it rarely can bring the TC down to zero at reasonable ozone levels.
Final point - hot tub ozonators are garbage and the industry knows it. Most of the ozone hardware slapped onto a hot tub are toys - their input gas is air (not pure oxygen) and they often employ a UV light source to generate the ozone or the use a cheap corona discharge (CD) tube. These units barely produce adequate or consistent ozone levels and, after about a year, they no longer output ozone at all. Real, commercial-grade ozone injectors use either pure oxygen or dried air (water vapor in air kills ozone output) to generate the ozone and the CD tubes used are typically field-replaceable because they wear out and need to be changed on a regular basis.
Now, if you plan to run a hot tub using bromine as your sanitizer, then an ozone generator is a good idea because ozone regenerates spent bromine (bromide) back into sanitizing bromine and bromamine compounds don't have the same cross reactions as chlorinamine compounds do. You still have to contend with the equipment issues of replacing the ozonator when it fails.
If you're running a tub with chlorine, simplicity would be my choice. Will ozone probably help out in a small, residential tub, sure. But it seems like one can get the same benefit by simply running a drape-over SWG in the tub. Chlorine works fine as an oxidizer and sanitizer and an SWG tends to generate some free radicals as well as chlorine so there is a good mix of powerful oxidizers there. Adding more oxidizers in the form of ozone just simply seems unnecessary to me and, for the most part, all it will do is create greater chlorine demand. Since there's no way to measure ozone residuals in water (they'd be very low anyway since ozone does not dissolve in water much), one is basically left to guess if it's working or not. This is why I'd rather just see the ozone turned off and avoid any unnecessary complexity and guess work. I can easily measure FC and CC and, if CC's build up, then simply dump the tub and start over. Even here in Arizona where water is more expensive than electricity or cable TV, dumping a hot tub every few months is really nothing at all....people waste more money irrigating plants that don't belong here or trying to maintain lawns in a climate not suited for grass.
Just my 2 cent opinion for what it is worth....
It just isn't going to go well... 