There are a couple of places where I can imagine it might be
    somewhat problematic, but they don't have to do with OO at all.
    The things that come to mind are debugging issues, like not having
    the complete call stack available for inspection.  I don't think
    this would be a terrible loss in most cases, but it seems to me
    that alot of Smalltalkers are accustomed to having a great deal of
    context information available in the debugger.

Scheme compilers typically allow you to run in "debug" mode which does
not do tail call optimization.

Also the Scheme compilers that provide first-class environments detect
when reflection is used and only become pessimistic in these cases. So
in Scheme, use of the procedure (the-environment) will return a first
class structure that has be "reified" on demand. The same could be so
with Smalltalk's "thisContext" special variable.

-- 
Patrick Logan                 mailto:patrickl at gemstone.com
Voice 503-533-3365            Fax   503-629-8556
Gemstone Systems, Inc         http://www.gemstone.com