FWIW, in my calling and dancing experience, the ratio of people actually dancing to those on the sidelines is better at the "gender free" events than the "traditional" ones.

Of course this makes sense if you consider the situation in terms of possible dance slots to be filled.

At the series I help run (Concord MA Scout House, Monday Contras), we used to get complaints (mainly from men but not always) about an "imbalance" in the hall and folks sitting out as they "couldn't find a partner". We shifted to Larks/Robins several years ago and that "balance" issue has never been raised since. Many folks do line up in a "traditional" couple - however, as 50+% of the dance pattern is done with neighbors and you're on average swinging your chosen partner for only 15% of the time...

-Don