2bit, is your faulty collision with terrain also include the "jitters"? In my applications, which are approximatly 100 single entity physics without any constraints, I have zero percent problem with fall though at any gravity setting (from 0g to ~200g) and within what I consider resonable velocities (less than or on the order of 1000q/s), but I have a big "jittering" problem where my entity jitters like popcorn on the gound and doesnt just lay there as it should. Marco had commented that this may have to do with the number and/or handling of the contact points.

As to your observation, I have a networked physics application where the client is registered with the PE upon login. Hence, the last client logged on is guaranteed to be the last player registered with the PE. I have observed no diffrent behaiviour from last registered to any registered...all my physics entities "jitter" seemingly at random.