Brian Gaff (Sofa) explained :
I'd have thought that one way would cover you in chippings and also pull you
into the tree if it jammed, but most Electric ones do not have the oomph for
that sort of thing. I've only handled one once, frightened the daylights out
of me, even when I could see.

I had to buy a petrol version and use it to deal with a fallen tree a
couple of years ago. Buying one and cutting it up myself, was the
cheaper/ simpler / quicker option. I bought a long bladed one, because
the trunk was quite thick.

I must admit I was at first very wary of it at first, with all the
stories of injury and risk of death, so I made sure I had someone with
me when using it. In fact it was much easier to use, than I expected,
it jammed several times and the clutch slipped to prevent any injury,
as it was designed to do. Tree had been blown down, so I only needed to
use it on the ground - I doubt I would have the confidence to use it
off the ground.