Yep, Serana has been beaten on by Frost Giants, Blood Dragons, Falmer, and pretty much everything in between, she's even fallen off cliffs and still lived. Which is awesome, because otherwise I'd have to reload any save where I lost her just to get her back, because of how awesome she is. Now the only thing we need is a patch to make either the dawnguard dogs essential, or let them respawn with new names after a while.