I went ahead and killed Parthy just for the sake of quest progression, and I was headed for disappointment.
Yay! So now I get to recruit three whole people into this 3 person faction! If they die, no more recruiting!
Yay! I get to have stupid bugs and journal entries like 'show Esbern some dragon bones' or whatever.
The Blades are basically finished right after you join them. How is that any good?!?
And their base is deep in Forsworn territory. How's that make any sense?

