Yep, I am also busy levelling a CoC bow based build. Biggest problem was when to switch to CoC to have it proc reliably enough. Still have a crit chance gem in my setup, currently get up to about 55% crit chance with power charges. I am in A4 Cruel now, lvl 54. As soon as I do the Cruel lab I can get the ascendancy buff for crit chance with power charges (in Assassin) and it should boost crit chance enough so that I hopefully don't need the crit chance gem anymore.
Current skill setup is Barrage+CoC+Bladefall+Glacial Cascade+Increased Crit Chance. With enough crit chance I can drop the gem to get increased AOE/conc effect for bosses. 6th link will be added chaos/EK. This setup is currently crushing the bosses I encounter, Dominus was quite easy in cruel. The knockback on crit also helps, last night Voll couldn't even get to me because the knockbacks keep pushing him back till he's dead