I will never...
ever use a MS upgrade or "migration" path. On the face of it you might be able to use w/e "new" software MS is flogging faster but at the end of the day you avoid so many potential headaches by installing fresh every time. Though I can sympathize that this might not be practical for the poor souls that have huge MS installs on the back end.
Of course this problem might not be upgrade related but the potential for untested use cases goes up dramatically when doing so. Ofc to be fair this isn't an MS specific issue. Just irritates me that they haven't learned their lesson in all this time.
That said I won't even touch win10 until at least the first service pack style rollup is available. Though that's perhaps contrary to the model they're advocating atm. I just don't see that being practical over a lifespan of 10+ years.