Bisexual and PansexualS

I know this debate has been going for awhile but I don't think I've seen it addressed on Groupthink. The mainpage article re: the nullification of bisexuality as an identity got me thinking about it again.

The short version is this: some argue that "pansexual" as a term is inherently biphobic because it presumes that bisexual persons would exclude non-binary-identifying partners, and that bisexuality never had that meaning before pansexual came into usage.

I raised this on the mainpage in reply to a person who suggested bisexual referred not only to binary-identified but cissexual binary-identified persons... which, yikes.

It seems an apropos discussion since we're talking about inclusiveness. What does everyone think? Especially GT'ers who identify as bi — do you feel that your sexuality is significantly different from pan, and do you feel that the creation of pansexual as a label makes an assumption about bisexuality? And GT'ers who identify as pan, how do you differentiate that identity from bisexuality?