None, other than for sheer performance. (THROW will perform worse than GO and RETURN since the list of catch tag will need to be traversed on each throw.) As y

None, other than for sheer performance. (THROW will perform worse than GO and RETURN since the list of catch tag will need to be traversed on each throw.) As you mentioned, one can implement both GO and RETURN via THROW plus gensyms - see https://web.archive.org/web/20191008050814/http://home.pipeline.com/~hbaker1/MetaCircular.html https://web.archive.org/web/20191008050814/http://home.pipel... for an implementation.