Hi Albert & Benji,
I've been using Ezoic for a couple of months. There are basically 2 methods that are used. One is where they change the layout of the pages and the other, less drastic (in my opinion) is where they experiment with ad placement.
I'm using the ad tester where I put 'placeholders' throughout my page in places that I'm fine with ads being placed. I can choose size of ad. Then, their ad tester experiments, placing ads in different locations with the different sizes depending on the visitor's past browsing and clicking data. At least that's how I understand it. So, when you're looking at a page on my site, it will probably have different ads showing in different places than if someone else looks at it. But, I have control in which places of my page they show.
As well, I'm letting Ezoic's ad tester work on 90% of my pages. The remaining 10% is Adsense. This gives me a comparison to see how things are going.
If you want to check my site, it's http://justlikeoma.com/
... to see what their ads look like. You'll need to click around onto my tier 3 pages, since that's where most of the ads will show up. Since most of my tier 3 pages have a similar layout, I only needed to place the 'ad placeholders' on one of my pages. Ezoic then finds similar page layouts and adds the ad placeholders there as well. So, the work involved in setting up was minimal.
For the time that Ezoic has been 'experimenting' ... my bounce rate and time on site are improving on the pages that are showing Ezoic ads. A nice side effect.
I added Ezoic to test how successful it is with my site. I'm giving it about 1/2 year before I re-evaluate if I'm staying with them. So far, things are looking good.
Hope that helps,