Is there a way to take a precomp and eliminate it and simultaneously move all the elements within it up stream to the parent composition while maintaining all keyframe data?
Funny enough, I've never had to do this until now, but another way to ask this is: can one simply move items out of a precomp into its parent?
Depending on how complex your nested (pre-comp) is you may be able to just select all of the layers in the nested comp, copy them, then paste in the new comp. You'll have to pay attention the the position of the CTI. Otherwise, invest in the script.
If you do just copy/paste keep in mind that AE pastes layers in the order that they were selected. So make sure to select them top to bottom.