> There is really not much needed to add to the 5125.

I think audio should be there. How to add that?

> it offers an e300/400 core just like the Efika 5200B.

Should even be slightly faster.

https://morph.zone/modules/newbb_plus/viewtopic.php?topic_id=7001&forum=3&post_id=74602#74602

> The inbuild gfx of the 5121 is rather weak

Compared to the 5125's gfx it's a powerhouse ;-)