I'm going to go out on a limb here and say that the Mormons who support marriage equality probably don't have any interest in taking y'all's advice to quit the church. That's because in general they believe in the Mormon theology and think that most of what the church does with tithe money is good.
And why would you want forward thinking people to leave the Church?
Our doctrine is broad, grand and beautiful. It is for everyone.
Decreasing ignorance and acting on evidence is a valuable way to make and recognize change.