I've played in amplified bands and sung through PA systems (sorry, but me and my mates have called them PA systems for the last 30+ years) from when Pontius was a Pilot. Nothing wrong with it whatsoever but - and it's a big but - I actually prefer totally acoustic sound in a club/session/singaround context. I know of two folk clubs near me that use a house PA for performers. One is very good, with a guy on the desk all evening, but there's still a bloody palaver before every performance as various people need sound balancing for the mix. The other club's PA is dire, but the organisers insist that performers use it because people "round the corner" can hear. Trouble is, it makes everyone sound terrible. I refuse to use it and use my foghorn voice to "reach round the corner"...

As for looping, if you ever get the chance to hear classical guitarist Richard Durrant looping Bach, jump at it - superb.