>>Written text's benefit is reviewability before its expulsion.
An interesting choice of words, Wanda! It might be true that some under-expressive people are a bit concerned about making errors or "making a mess" if they say things without forethought. There might be some compulsive tendencies (I'll let the Freudians apply their more specific terms!). As a compulsive person from way back, I know I like to "get it right" - which is why I like text talk.