How can Boomer be the final cylon when she is a Cylon already?
It'd be really complicated... not one of the brightest notions around the internet. But RDM could always surprise us and make that notion work.
Why not? How can Tigh be a Cylon when he is a human already, an old, aging, human, at that?
I would say, apples and oranges. Its actually easier to make the jump that Tigh and friends are Cylons then to some how make it work that a Known Cylon with many sisters is also the "Final Five" Cylon. I can accept the Final Five are different in nature some how. Not so easy to work out the logic of Sharon/Boomer's model is somehow not akin to her fellows.