Nope, not for me at least. I actually had Imp CoC and 2 in Permafrost when I used the 10/0/51 build, but in order to put some into Arctic Winds for the next patch we have to drop points from somewhere. Some people ditch Frost Channeling for Improved CoC. Frost Channeling makes somewhat of a subtle difference, but it's a very big difference (much more than Imp. CoC) in the long run. You could drop Ice Floes and maybe one more point out of Winter's Chill too if you prefer Improved CoC. You could drop Arctic Reach too I suppose. Whatever suits you best, I simply find those other talents to fit my playstyle better.
CoC is very inefficient on mana unless you're AE farming a lot or PvPing a lot. I did like it for AE shatter farming, but I rarely did that once I reached outlands. With enough mana regen and +Dmg you reach a point where single target farming is much faster, mainly because you dont have to rest much.