AO: if you have a good combination of time capacity and skill, I suggest you give it a try. AFTER full 1:1 backup = mirror copy of your existing harddrive --> so that you can come back any time you wish just by dumping the old disk image into place.
One reason only: during the upgrade MS will authorize/register your MoBo as W10 licenced, and thus anytime later you could do W10 for free. And who knows, maybe it will work for you ok the first time around? It did to a large number of people ...
Good luck either way.
In general, mirror copy of HDD is not actually a bad idea irrespective whether one chooses to try the upgrade or not.