You are right the small movement looks really weird in the Case,
but I can confirm it runs really good and smooth.
It is normally a Day Date movement like the 2836-2.
The pinions for the Hands are slightly longer as on a 2836-2 so
there is a bit more space to the dial,that's good in my opinion.
Date change works perfectly.
I dissambled the watch tonight and the movement holder is
Very good machined.
The Dial will fit a Eta 2836-2 without problems.
And now the bad news, the Hands won't fit the 2836-2
Pinions. So if you want to swap the movement you need
some other Luminova Hands