Yes, right… . For me Quaternions where done once I have had them implemented in the Add-On for Blender and still I do have troubles with them. “At the moment” I am trying to implement a load-function so I can load existing animations into Blender. Everything works fine, but… sometimes it seems like if I load the animation some limbs are turning in the wrong direction to the final position. So instead that they turn like 10° cw, they turn 350° ccw, which does not make too much sense and looks weird. My assumption is that this has to do with the funny Quaternions and the way they are handled. Let’s see if I can fix this bug anytime soon (in this case there will be a new feature in the Add-On) .
Maybe posting about the problem could help get it fixed? When does it happen and whatnot. For all we know it minus be a missing minus or something, it might be a problem with python as well, it has a few traps in there.
I think I have already isolated the problem. It has to do with the way Blender handles objects with relationships. Just need to find motivation to take a look into it.
I can run to your house the shortest way, or run 180 degrees in opposite direction and reach you by running around the earth. For blender this seems to not matter, which is indeed weird. Why it does not take the shortest route?
Animation incompatibility will be problematic. But the modeling interface of this software is really intuitive and the programme is really light it’s cool for people with bad internet connection like me.
. For me Quaternions where done once I have had them implemented in the Add-On for Blender and still I do have troubles with them. “At the moment” I am trying to implement a load-function so I can load existing animations into Blender. Everything works fine, but… sometimes it seems like if I load the animation some limbs are turning in the wrong direction to the final position. So instead that they turn like 10° cw, they turn 350° ccw, which does not make too much sense and looks weird. My assumption is that this has to do with the funny Quaternions and the way they are handled. Let’s see if I can fix this bug anytime soon (in this case there will be a new feature in the Add-On) 
