[TikiTDO]

There are some other very important advantage of text that I feel you omitted. First, the ability to simultaneously carry on discussion on multiple topics all at once is a huge factor. In a normal, face to face conversation following an interesting but unrelated line of thought can sidetrack the entire conversation, often beyond the point of recovery. When you move to a textual medium you can easily carry on two or even three topics provided that both sides can keep track of the various conversation contexts all at once. Best of all, you can follow up on these branches in conversation even while the other person is typing.

That brings me to the second huge benefit. When talking, you will very rarely speak at the same time as another person. Not only is it rude in basically all cultures I am familiar with, it also makes it hard to follow what either person is saying. With text there are no such limitations. When you consider that an average person can read up to 300 WPM, while someone that has practiced speed reading can easily break 600, it is not too infeasible that both sides of a conversation may be typing the vast majority of the time. For those well practiced in text-based communication this can greatly increase the average amount of information transfered per unit time, easily negating the difference in typing vs speaking speeds, and possibly even improving upon it.

I do agree on your notes about body language and emotions. I have lost count of the number of times I have seem people interpret sarcastic textual statements to be completely serious. On the other hand I find that people get better at recognizing even that when spending enough time reading chat/comments online.