I don't know about Apple's opinion of the GPLv3. My opinion, however, that there's a real problem with GCC's GPLv3 Runtime Library license exception. For instance, does the exception apply to a separate libgcc.so? The FAQ suggests that it should, but try coming to that conclusion from the exception language itself. IANAL, but I believe that this would make it impossible to build many kinds of closed systems with GCC even if there was no other GPL'd code on the box. I know for sure that issues like this are scaring people away from the v3 licensed compiler.
Also, re: libffi. There are many copyright holders. All but one (a major non-Red Hat contributor) agreed to sign assignment papers to the FSF many years ago. This was enough resistance to stall my efforts. In retrospect I'm glad this didn't happen, since it probably would have been relicensed under the current v3 runtime exception license.
I hope this is an honest mistake that the FSF can correct or clarify soon. I've reached out to them a while ago.