Current GCC packages

Is there a reason why not to have the newest gcc packages released at

installed at OMV 3.0X? Stability?

We don’t usually backport things like new compilers to “old” releases because that may trigger odd behavior (recompile a package that is part of the release and its size, speed and potentially bugs are different from the exact same package before it was rebuilt).
Usually new compilers go with new big releases (clang 4.0 and gcc 6.3 (or 7, probably out by then) in 3.1).
We do have the current versions in cooker - and there’s no reason why installing the packages from cooker on 3.0x wouldn’t work.

To avoid breaking packages, it would be interesting if I could have newest gcc packages installed as an alternative to the regular system gcc. For example, in some /opt/gcc-6.3 directory.

Is there a way to install gcc-6.3 without root privileges?