I can bring to mind at least a few situations where a singaround would be preferable to an organised concert.

It all depends who you might hear at either and if you are pretty sure that certain individuals or groupings would be at a singaround then it could detract from a very average (subjective) concert.

The young Wilsons in the days of the Sun Folk Club in Stockton was at times just such a situation and to a certain extent was not helped by Ron Angel's treatment of floor singers at the time.