> This will not nuke the symbol keys if they exist, right?

Correct, but since we prefer string keys on access, I don't think it should matter.

> If this is a hash with indiff access, we probably want deep_stringify_keys.

We don't convert nested hashes to have string keys on access, so I do not think we should deep stringify. This is inline with not allowing symbols (or hashes with symbols) to be stored in the session object and the same principle followed as access within flash objects (keys can be symbols, but you cant store hashes w/ symbols).