Is it really worth the money compared to, say a used PSR-S950? How do the sounds and features stack up against a PSR from two generations ago?

Based on a thorough reading of the manual, it's my opinion that Medeli licensed or borrowed key parts of its OS from Yamaha. At the heart of every arranger is chord recognition, and Medeli omitted (or was unable to license) Yamaha's "AI Fingered" system, which is their most advanced mode, and IMO the only one worth using. Think also about a lack of third party or legacy styles. So what is the unique feature or key value proposition here?

My Daddy was an engineer and he always said, "Build a better mousetrap, and the world will beat a path to your door!" If I'm critical, it's because this isn't a better mousetrap; it fails to advance the state of the art on any frontier. They're just reselling a mature or reduced feature set at a lower price point, which will ultimately plant the seeds of remorse in the buyer. When Medeli's engineers come up with something unique and compelling, I mean really move the needle, then I would consider their product. I hope they keep trying. My $.02.