Oh, you left me nothing to post.

You said everything I was going to say Byakko. lol
Except the bit about it sounding better, I still think there's something ruggedly appealing about the word Were, Therian seems a bit softer somehow. Still that could be an age thing, I grew up with Were, Therian is still quite a new word for me.
I don't think there's a difference really either, it's a case of personal preference and what you feel most comfortable with.
I'm with Byakko on the physical shifting aswell. Not that I'd ever though it possible, being one of those 'sane' types that Byakko mentioned, but also I read Wraiths post on it and was very impressed with the way she explained it.