Don't do this trade. Crosby is a top 3 player in the league, and Backstrom takes much of his value from playing with Ovechkin; were that situation to change, Backstrom's value would decline quite sharply, but you run no risk in this way with Crosby, since his value will always be the same.
He's also worth more. I wouldn't be trading Crosby unless I was getting Ovechkin/Malkin in return... or at least 2 or 3 superstars of Backstrom's ilk.
Currently drafting keeper
12 team roto, daily lineups
G,A,PPP, +/-, PIM, SOG, Faceoff Wins
W, SO, GAA, SV%
C: Tavares, Zajac, Brassard, Filppula
LW: Parise, Clowe, Penner, Bourque
RW: Hemsky, Giroux, Alfredsson, Radulov
D:Myers, Yandle, Carle
G: Rinne, Ward, Gustavsson
Farm: Filatov, Hodgson, Wilson, Skinner, Grabner, Sbisa, Moore, Stepan