I haven't found a strict ordering, though, for which is better at tougher issues. Sometimes face-to-face is much quicker, especially if it's hashing out high-level disagreements or overcoming misunderstandings about motivations and general directions. Sometimes for architecture or deciding on features or cuts as well. But when arguing more complex technical points, I prefer LKML-style discussion, where you intersperse code and text, and have time to properly research a serious reply.