I have heard that this is a good way to propagate blueberry plants. Are
the resulting plantlets vigorous?
I'm afraid my opinion is a cryptic answer: the ones that live are vigorous.
If you want 20 plants, set out 60 cuttings. Half will die and a third of
what's left will puny. But in he end you'll get your good 20 plants.
"Layering", the second method, will give better plants especially if you
prune off 3/4ths of the stem when you dig it. In a few years you can't
tell the difference between the mother plant and the ones from cuttings.
Blueberry plants live a loooong time.