I never understood the stability argument. The teeth will be stable no matter where they are in the bone so long as they're held there for a few months, giving the bone time to settle on the new tooth position. The real issue is that once retention is removed, the forces around the tooth may move it back. However, that's not an issue if you're fixing a force balance issue by moving teeth into the right position. OTOH, I had braces as a teen and wore my hawley and night guard every night since and only two decades later my teeth are messed up again.
I'm looking into it for myself but mostly only because my case seems uniquely tailored for it. I'm a borderline case for a 3-piece. I only need a few mm of expansion on the upper arch and my front segment can be leveled with a little tipping. My concern is that afterwards I won't have much bone margin which means that I may develop periodontal problems and root blunting, both which PAOO seems to address. Otherwise, I would say that the main benefit is reduced risk of root resorption, especially for longer cases. However, given that the RAP exists after jaw surgery anyway I would say it's only useful pre-op and the same benefit could be achieved with Propel, avoiding the surgery. As for stability, to my knowledge that's still unknown. There are no long term studies on this stuff.
As for expanding the arches, I don't buy the argument others here have about it causing joint problems. However, teeth are impossible to replace so you really don't want to lose them. I would give PAOO a shot to avoid extractions. Osteotomies are possible to lengthen or widen the arches but not commonly done because it means an extra surgery and more complicated orthodontics. Orthodontists like to create plans up front in an hour or two then put you into the pipeline. Individual cases requiring babysitting cost them money and those that have time for it, don't have experience to do it so it has to be someone with a passion for complicated stuff.
I'm largely unimpressed by orthodontists so far, I don't know what these guys learn in school but they seem to cause a lot of problems in this world and lack fundamental understanding of a lot of topics like facial development, orthognathic surgery, periodontal problems, etc Pretty much all the topics orthodontists should know.