You are talking about c++ in your pages, 3.4 compiler can be used even for c++ if you link stdc++ statically, see thread about scummvm. The only catch seems to be when loading c++ code dynamically (i.e. some plugins in .so files). This may cause problems when the plugin is linked dynamically to libstdc++. Also for c++ '-fno-exceptions -fno-rtti' kills some bloat that is rarely/never used in most c++ code.

For linking stdc++ I use shell wrapper over original g++ that adds -Lpath to path where is only the static library. See some tips here http://www.trilithium.com/johan/2005/06/static-libstdc/

EDIT: sorry not scummvm but the optimizing .deb flags thread