Well, i guess you can do whatever you'd like. If your sub is right next to your panel, which it looks like it will be then it would be completely unnecessary to buy a main breaker panel. If it's in a seperate part of the house then why not. I mean, we're all for the AFCI's right? Let's over-engineer our equipment but not give ourselves the means to disconnect the power manually just in case.
Wet Reefer, I'm glad we can all be mature enough to take jabs at others that are trying to help. I disagree with many of the things you've said based on personal experience as an electrician. I've known many of the book-smart types that can quote codes but can't do the work. I don't know if that's you, but it kind of sounds like it. Call me not so brilliant if you want, but I've got an IQ, GPA and ACT scores that say otherwise. That's not nearly as important as the fact that there aren't many electricians that I've worked with that can outdo my work. The key is realizing you don't know everything, and the ability to learn.