Oh goody. I think i'll just stick to my double enchanted Daedric longsword (named Morgoth's Fury).
It just seems unfair on non vamp players. Vamps become this badass demon thing, but the slayers only get a set of gear that will still be most likely outclassed by custom stuff.
if all that matters to you is the reward then it seems kinda that way. honestly though, we know very little about the dawnguard aside from a bit of general info. the dawnguards quests could be way cooler than the vamp quests. we dont know. you just have to wait and see
i also dont recall ever seeing that dragon bone weapons would be only for the dawnguard, unless someone has a link with confirmation, i dont believe that they are exclusive.