this is an old aged conundrum.
do you go for sis, or do you not. it has both pitfalls and bliss.
if it was my sister, my protectiveness as a brother should also be conveyed by my bros and they should treat her as a sister as well....
BUT....
in the end my sister went for whoever she chose and if they didn't treat her well the ones i could find were slapped silly.
the ones who i was friends with when they broke up it was on good terms and i still talk to them, hell even the ones that didnt go that well i still talk to.
I guess what im getting at is...whatever we may feel about our friends dating our sisters, there's nothing we can really do about it because in the end .....
family>bros>hoes(or sisters)

who wants to have a sister hate on you?
another thing...
my bestfriend is my SO's brother....we still talk about sex and all that shit but sometimes i'll say " bro i'd tell you about this one time but i'm pretty sure you don;t wanna picture your sister in that way"

go figure.