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