I appreciate that FloraG was asking specifically about morris sides, but as a member of a trad duo I feel I can comment.

We played three times at this year's Sweeps: once in a pub with our own small PA, once on an outdoor stage with full PA and once unamplified on the wonderful sailing barge Kitty.

I think the use or not of a PA depends to a large extent on the venue, both in terms of its size and also its clientele (quiet listeners, loud revelers etc).

We usually play with a PA, but welcome the opportunity to play as nature intended. Playing on the Kitty was a delight!

A lot of morris sides have become very drum heavy, so a PA makes sense (as does fewer drums).

Gordon