Great points, but even my girlmath keeps thinking about this:

"...some 75% of surveyed lesbian, gay, and bi people told Pew Research Center that they were accepting of open marriages last year, versus just 33% of all adults. With all the extra attention, one hopes the 77% of Americans who aren’t open to open..."

I'm currently in my first poly relationship of about 7 months, and I gotta say it's shocking how not-wierd it is. I knew going into the relationship that partner was poly and had a boyfriend, and I decided to set aside my preconceptions and I'm glad I did. I'm sure I would feel differently had my partner not been open, honest, and mature, but the same could be said of any relationship.