In manyclangs (which uses elfshaker for storage) we arrange that the object code has stable addresses when you do insertions/deletions, which means you don't need such a filter. But today I learned about such filters, so thanks for sharing your question!
In this comment, you say "20% compression is pretty good". AFAIK, usually "X% compression" means the measure of the reduction in size, not the measure of the remaining. Thus, 0.01% compression sounds almost useless, very different from the 10,000x written next to it.
