The original issue had 2 parts:
First, the timer to set Rag Doll after the montage was set up incorrectly (Fixed in UE-27876). Second, the Death montage blended out, so the character would pop back to his initial position before enabling Rag Doll, which triggered a flip-flop for one frame. (Fixed in UE-28053).
When testing the last issue, I saw very minor popping as the animation transitioned from programmed animation to ragdoll but a great improvement on the original reported issue.
Do you not find this to be the case?