I've heard Lord Bateman, Young Hunting, Tam Lin and Little Musgrave done in singarounds, and never been bored. The only boring long ballad I can ever remember sitting through was a performance of Sir Patrick Spens (the long version, where they sink on the way back) - and that was only boring because the singer was also an accomplished guitarist with a knack for improvising twiddly bits between verses, and thought it would be a good idea to show off this skill after every single verse. (Also because I was hoping to get called myself some time that night. Which I didn't.)