I understand your "new toy syndrome", Oxydator was one of such purchases in my case
I have it in both of my tanks, two small models in 180l for more than a year, one small in 16l since the start several months ago. Content lasts about a week with 2 or 3 catalysts (not all are "equal" for some reason) and 2-3 weeks with 1. I realized, that I forget to top it up in my small tank very often, so I'm running empty Oxydator probably half the time. Frankly, I can't tell the difference in the small tank nor in the big one. Fish behave the same with or without Oxydator. Plants grow the same (as far as I can tell). ORP doesn't seem to be impacted either. I do not have any option or need to measure available O2 in the water, but I expect to have more oxygen with Oxydator than without - not enough to make plants pearling though (I'm not using pressurized CO2). So it certainly doesn't release huge amounts of oxygen.
It's an interesting gadget and probably has benefits in certain cases, but I do not see it as a "must have". I certainly wouldn't use Oxydator as a direct replacement of bubbler or strong surface agitation.