Reading this thread I can't help but recall a phrase I once heard about "folk song in evening dress" (anyone remember where that came from?).
I've no basic objection to choirs performing folk songs (you'll be relieved to know!) but I, personally, don't find such communal performances terribly exciting or convincing (though I may admire the technical skills and musicality of those involved).
It seems to me that British folk songs - particularly English folk songs - are best performed as the old singers performed them - unaccompanied. This style of performance emphasises those two aspects of (English) traditional song that continues to make it exciting for me: melody and narrative - precisely those elements that can easily get lost in a choral arrangement/performance.