My experience has been that they are far too unpredictable to be of use.
In my testing with agent networks, it was a challenge to force it to provide a response, even if it was imperfect. So if there's a "reviewer" in the pool, it seemed to cause the cycle to keep going with no clear way of forcing it to break out.
3.5 actually worked better than 4 because it ran out of context sooner.
I am certain that I could have tuned it to get it to work, but at the end of the day, it felt like it was easier and more deterministic to do a few steps of old-fashioned data processing and then handing the data to the LLM.