Sorry it took me so long to get back to you, I have been busy the month or so with retirement stuff. I was MEDEVAC'd and placed directly into a warrior transition unit where I have been since Oct 2007. I went through all the treatment and it was decided that I was unable to serve in my current rank and MOS (Infantry E-8) so I was sent to a MED board then a PEB.
It is tough to get 75% just for TBI. from what I was told you would need to basically need to be a zombie to get that much. I received 80% but I had other injuries due to the IED I was in. I received 40% just for the TBI.
Make sure you are going to the doctor when you are told and do what they say, it will help your case when / if you end up getting a board as well.
Your VA claim later will pay good as well since your injury is combat related.
let me know if you have any more questions, Kevin