Is it even worth switching from ARMv7 to ARMv8?
Not unless you are running a kernel and OS userland compiled for ARMv8; there are at least a few such things for the Pi 3 around, including Fedora. For some hints about why there still isn't a special version of Raspbian, see here:
Otherwise, I think the only relevance is in what the processor reports itself as, which can be found via /proc/cpuinfo. Some people use this as a means of telling one model of pi from another, although the practice is obviously not widespread. Put another way, unless you know of a reason to do so, there isn't one.