Is it worth switching to SU 16 beta? I am only wondering if it improves performance and reduces stutters. Does it really do anything different compared to SU15?

I suppose the official SU16 is close to release, so maybe it's better to wait for it a bit. After SU16 is released it'll be no way to get back, as we all know.

In the official forums there are numerous complaints about the unacceptable quality of the ground textures in some areas, due to the change in maps to be used by SU16, to be the same used by MSFS2024. There are people saying the affected areas are less than 80% (they're probably throwing out a number), while others says is almost everywhere.

Look here:

https://forums.flightsimulator.com/t/msfs-su16-aggregation-of-complaints-about-poor-lod-low-resolution-blurry-terrain-textures/731741

I'll continue to enjoy SU15 as much as possible, since nobody knows to which extend SU16 beta will be corrected on time before or after its release. There's always the option of using the Map Enhancement Tool with other Map providers (many in case you have the licensed version, of a few, mainly Google Maps in case you don't).