Here's a video demonstrating some of the differences:
https://www.dropbox.com/s/90gltxwyltiriiw/newtoncompare.mp4?dl=0
- The momentum change on collision of the bodies is very different. The new version is much stiffer with the sliding body losing almost all velocity on collision, and even moving backwards.
- There's also some strange upward motion on the red disc at the end. It looks like some slow de-penetration, though there is no penetration.
- Not shown in this video, I have seen some other bugs with bodies not sliding across each other as expected, and other strange rotation/movement when a body should be at rest against the ground.
Are these differences to be expected? If these are bugs, where's the best place for me to look at why this is happening? What is the most recent, stable version of Newton you recommend?