Couldnt agree more Bob, about not all 3/4 tunes suiting waltzing, or 2/4 tunes suiting polka-ing.And there's more than one kind of 3/4 waltz, as musicians soon find out from irate dancers or callers. Musicians would all benefit from dancing occasionally, but some of them don't dare.
Re my previous posting on early hornpipe tune notation. A lot of them were published or written in MS in 6/4, but they aren't IN 6/4. The 6/4 is an error. They had three main beats in a bar, which is why 3/2 is appropriate. 3/2 and 6/4 both have 6 crotchets in the bar(but subdivived differently). That's how the confusion arises.