I was in Ireland a few years ago, midsummer and pubs all very crowded.
Some places had a mike hanging above the table where the session players gathered. That was only a very low powered amp and did a good job.
I still think that you cannot improve on the natural acoustics of a good room. The subtle harmonies that can seem to float around the room just don't happen when amplification is used.
My gripe is against UNNECCESSARY amplification. I know of several "folk clubs" which do have an attentive audience, held in quite a small room that does have good acoustics but short of an act of god like a power failure the organisers will insist on stuffing around with microphones and also put on background music in between just in case you might be tempted to have a quiet chat with your friends during the break.
This is a bit off subject but I have been in accapella choirs for a long time, when we perform acoustically in halls, it is always good. When we do an outdoor performance and are all strung out in a line with a shared mike for each section of the group..it is almost always a disaster. Only the singer closest to the mike is heard, we can't hear the blend in the foldback and the sound engineer keeps turning up the gain until it is at the point of howling feedback.
Anyone got any tips to improve that situation? I think we usually have the wrong type of microphone (designed for up close use) whereas what we probably need is a central mike that can pick up the overall sound.
Problem with that is that type of mike is more prone to feedback if amp turned up too high.