Have Samsung now taken your idea? After a recent software update I noticed the following...
When I choose motion photos in my gallery and choose to share them I select the ones I want as before and then it gives me the option of saving them as video or photo files and then saves them to the same album. It does not direct me to several sharing types where I select your apk...?
In fact although I have not deleted your apk it now does not show on the list of sharers anymore so i cannot use your apk anymore?
---------- Post added at 07:32 AM ---------- Previous post was at 07:31 AM ----------
If I choose the option of saving as a video file your apk doesn't show in the list, but if I choose the option of saving as an image file it does and then can go on to save a gif as usual....
It would be nice to have slower gif options too.
I wonder if Samsung can be convinced to make the Motion Photos longer than 2 seconds.. I would prefer about 4 seconds myself.
They haven't really taken my idea as such as they have implemented the feature they should have always had

I think it's great they have responded so quickly and built it into the system.
As for the Motion Photo Sharer app, as you noticed, it now supports exporting to animated GIF support so hopefully some people still find it useful for that (plus it has multi-motion photo export).
And yes to use it you will need to share as picture as the app reads a motion photo (jpg) not the video itself.
When you say slower GIF options, what do you mean exactly? Right now it exports the speed based on the timing of the video.