Right. So, in order to make sure that we're as close to Hash as possible, I'm leaning toward having `to_hash` on 4.x, then remove it in 5.0. I know that it's risky, but since this is a minor release, I'd want it to break the least number of apps possible.

Or, do you think it would make more sense to keep inheriting from Hash, with deprecation warning on risky operations that will override permitted status, then wait until 5.0 to pull the plug?

I'm not sure what would be the best solution though, as we're pretty much breaking the compatibility while trying to maintain it. :smile: