I've spend a lot of money recently fitting the best pickup systems I can find to several instruments and, properly amplified through a good PA or dedicated acoustic amplifier, the sound is very close to my acoustic sound only louder and with freedom from being rooted to a microphone. A year or two ago I was a great supporter here of good microphones for acoustic instruments but eventually got tired of sitting or standing immobile! The choice of microphone and placement is also crucial and one is also at the mercy of soundpersons of sometimes questionable ability.
Like Willie-O, I think correct setup and placement is essential and pickup systems have improved vastly in quality over the past couple of years.