Ordered
I got my invite last night. I signed up this morning. Should have the Nexus 6 tomorrow. I am a heavy Google Voice user, so some of the things regarding it are not entirely clear to me, but I noticed that if I didn't "port" my GV # into it, it made it appear as if I might lose that number, which I definitely do not want to do. So, I ported it in. It looks like if I cancel Fi, I can keep my GV # though.
Still not crazy about the lack of a MicroSD card or removable battery, but I like to experiment and this will be my backup phone, so why not?