For now, seems that you have to settle on Storable, as there are quite a few serious bugs in Clone.
However for long term, it seems Clone would replace Storable, so expect to migrate to Clone:
Although Storable is also optmized, but its dclone is slower when compare to Clone's clone. This is easy to understand, as dclone is not the focus of Storable.
The dclone function in Storable is kind of quick-and-dirty solution, it simply serialize the data structure first, and then deserialize it to create the clone. Although it is optimized to share data between step one and two, it still does lots of things that are needed for serialization but not pure cloning.
The functionality of deep clone should stay in a seperate class.