I wrote a blog post about my findings, including photos
https://blog.chschmid.com/?p=3135
For me the Yamaha YSL-548 came out as the winner, with build quality being the decisive factor.
Here some photos of the Rath R400 right as it came out of the box:



What are your thoughts? Is this to be expected for a trombone in this price range? Am I overly critical? Did I miss anything? How would you argue for one or the other?