I prefer to type my posts, which forces me to be as concise and precise as possible (two perhaps contradictory goals). It helps me to avoid stream of consciousness infecting my posts with tangents, and helps me to organize what I want to say in a sequence and format that I think makes my thoughts the most compelling they can be.
To me, it's not the length of the post, it's the thought journey that I take the reader on that's the objective.
-PJ
There you put it precisely in a nutshell.
As to typing versus dictation, I find just the opposite, I feel freer when I dictate. But this was not always so.
My first exposure to dictating came with a live secretary when I was assigned a long writing. I could not seem to get started on my first assignment or to give my secretary anything to put down in her book. The boss came in and said, "kid what are you doing?" I mumbled some sort of incoherence and he said, "let me show you." He walked around the long conference table consulting books and dictating as he went. Soon my secretary had her book filled so he called in his own secretary and continued.
When he had finished he looked at me and he said "kid, you cannot write it if you do not write it" and turned on his heel and walked out of the conference room.
I learned how to dictate but I never learned how to proofread. Once more thing I did smart, I never let them know I could type.