Yup. Everything shoved into the dictionary named Smalltalk, including "isA" methods for every subsystem you've written shoved up to Object isn't a big deal for in-house development. When you publish a library or grab one from somewhere, then it becomes a big problem. Then you want namespaces.

So the real-world experience for Smalltalk is that the former is mostly FUD. The latter is a real issue. I suspect that this pretty much applies to the other dynamic languages as well.