Originally Posted by
Conjugate
The negative impact - if you don't have the macro, you can start your next cast when your current channel is (your latency here) ms from ending, and fire off the spell just as the channel ends, however if you use a nochanneling you lose that gap and guarantee your next spell will be (your latency here) ms delayed at least(can be even more delayed, depending how frantically you smash the keyboard). However it is far less risky and many(me included) choose to go for it.