A balancing anecdote;
We bought one for practice, partly out of a sense that if supermarkets and the rest have them, it's a little embarrasing if we don't, but with no expectation of using it.
We had someone arrest whilst sat in the waiting room, did CPR, used the AED which found a shockable rhythm, shocked twice and by the time the ambulance arrived patient was breathing spontaneously with a good output. Subsequently left hospital well, with an implanted defib.
We felt very good.
Adrian McLachlan
www.hetheringtongp.co.uk