Good question.. Good answers..
I mean when Dawn first appeared on the show, I couldn't stand her--she was like.. well, an annoying little sister.. but her character grew and grew on me so I don't hate her as much as I used to. (("Look, she's posable!" lol))
Anyway, when the glowie light, or whatever Willow did to find the potential, found Dawn my first thoughts were "That's just not right".
I can't remember if it was because I knew she wasn't, or if it was because it would be too cliché, but I knew it wasn't right. (I mean, why not give Xander magical powers, or Anya, or Andrew, or the guy down the street--I never liked the idea of the potentials, it was just too farfetched. But, okay, there had to be a big-bang ending so why not fill the world with slayers.. right now Buffy can get some rest and have some fun"”show over.)
Anyway, my point is that it would have been really "˜dumb' for Dawn to have been given powers"”if the world is full of superheroes, then nobody is different or special, and there really is nothing to write a show about. HOWEVER, after the thought marinated in my mind, it started to appeal to me"”imagine you're Dawn and you see the life of solitude your sister lives, then think of how that life would be yours once she is dead"”gives me shudders.
When we found out it was Amanda, even though you could tell it was obvious, I was actually disappointed"”NOT because I wanted to see Dawn take over, but because of how she felt, and then came the Xander speech? I can't remember the order, but I remember how moving it was and, in the end, that was "˜right'.
The blood thing, wow. Um, my only thoughts are that Dawn wasn't a "Clone". She was made from Buffy's blood, but she wasn't "Buffy""”kudos for whoever thought up that one though.
For the record, I always assumed that Dawn would pick up the witch trait, since she'd always hang out with Willow and Tara"”but she started fighting on her own, and that is why I admired her in the end.