man, I have not been here in a while and will dive right back into the discussion.
Yes Spilly, you are correct that it is indeed in E.
However, stating b mixo is helpful to setup your phrasing. By saying its in E implies that you run from E to E. Do that over Fire and it does not sound right. B mixo implies to run E major from B to B. Do that and voila! you got it nailed. It helps because there is really no E chord in FOTM to really nail down that E major scale.
If everyone has a better understanding of modal theory its much simpler to say B mixo than
Start on B, run through the Emajor scale for a measure, hit an A, run around Emajor for a measure, hit a B............Continue prossess.
I get frustrated, though, when I hear its in B, because it starts on B, and people use the (il)logic of assuming that the first chord is always the key. Especially with most Jerry songs, they almost always start on the V or the IV.
And really dude, where else do you get technical about this stuff other than a Grateful Dead music theory board.
Information is not knowledge. Knowledge is not wisdom. Wisdom is not beauty. Beauty is not love. Love is not music. Music is the best.- the girl from the bus