I consider myself a 4A/B. I would be so afraid to put a texturizer in my fear for fear that it would straighten out entirely, since so many of the texturizer "success" stories seem to be on hair in the 3-range. There are some examples of type 4s texturizing on the Curve site, and most of them look nice, but I don't trust myself to do it, nor do I trust anyone else to be up in my hair, either.
I want to stay natural, but I know that as my hair grows out, it will become more difficult to handle ... that's what made me cut off the 12+ inches I had before ... it was just too time consuming and difficult.