Does it matter that I update the gcc 4.6 to 4.7 or higher in Ubuntu 12.04(LTS)

Does it matter that I update the gcc 4.6 to 4.7 or higher in Ubuntu
12.04(LTS)

I found that more and more open source libraries will use C++11 features,
and my Ubuntu Desktop 12.04 just has gcc 4.6, I want to use the
update-alternatives to change the default gcc version into 4.7 or 4.8. I
wonder that, if the libraries in the /usr/local/lib compiled by gcc 4.6
will need to be recompiled by the new gcc 4.7/4.8. In my opinion, if the
dependency libraries are still in the system, there is no need to
recompile. But, If one dependency library compiled by the new gcc 4.7, is
the dependency among libraries still right? Sorry for my poor English.
Thanks.