Gary,
Usually one is right to be wary of upgrades to complex systems; things can get… ‘lost’.
But in the case of Stacks 2 > Stacks 3 not only have I made the upgrade myself - 100% seamlessly (everything just picks up where it left off in Stacks 2); but I’ve also seen next to no posts here suggesting that there are problems. In the case of PlusKit, which surfaced today, you can be sure that if Isaiah says he’ll fix it, he will.
You can upgrade without fear. Really!