Etching (especially with joblib.dump ) is useful for short-term storage, for example. to save partial results in an interactive session or send a model from a development server to a production server.
However, the etching format depends on the definitions of model classes, which can vary from one version of scikit-learn to another.
I would recommend writing your own implementation-independent save model if you plan to hold the model for a long time and let it load in future versions of scikit-learn.
I would also recommend using the HDF5 file format (such as used in PyTables) or other database systems that have some support for efficiently storing numeric arrays.
CSR COO scipy.sparse, .