Makes it sense to use newer versions of gcc-compiler (4.5.3) from macports instead of standard compiler per default provided with xcode (4.2.1).
I'm don't develop any Mac related programs. I'm working with C++ in Eclipse. Would I benefit from newer gcc version or i would get a lot of compatibility problems?
The GCC that comes with XCode was tweaked by Apple to their Operating System. Stick with the default if you don't need specific features from newer versions available on macports (which, by the way, were not build by Apple).
Replacing xcode with macports software
Also, check the interesting notes of UsingTheRightCompiler before adventuring on that.