The Scheme community has a process called SRFIs which models on IETF RFCs to explore models and extensions to the standard language (I was one of the founding editors of SRFIs). Although Scheme is not (usually) OO, it is dynamically typed and has many of the same issues as Smalltalk.
In particular, they have recently been discussing many of these issues as part of SRFI-77, at: http://srfi.schemers.org/srfi-77/
In the Document, look at the Issues under the Design Rationalle section.
You may also find much of the archived discussion relevant.
../Dave