I'm concerned that the military doctors may be too close to the "system" to provide a proper assesment of effective military performance. Should I seek an outside psych eval? Does the PEB typically default to military docs over civilians?
This is a decision you should make with your attorney's advice.
My own thoughts on this matter are that the weight given to an outside medical opinion depends on many factors. To start, yes, the military docs are given deference and weight to their decisions.
However, in some cases, a civilian doctor's opinion will be given greater weight. The factors include, whether this is an independent medical opinion in the absence of a previous therapeutic relationship. If you are only seen one time for the purpose of the getting an opinion, then this may be seen as a "paid" opinion and, thus, not objective. Other factors include the education, professional qualifications, scholarly writings, basis for opinion and experience of the doctor. The opinion of a newly minted psychiatrist, from little known State U., who only reviewed the patient's mental health records will obviously not be given as much weight as the opinion of the Dean of Psychiatry from Harvard University Medical School, who has seen the patient over a course of time.
Another factor to consider is the purpose of the opinion. If it is to sway the PEB, most times the member will have no luck with an outside opinion, in the absence of profile limitations or evidence of duty limitations. And if you have the preceding, the military doctors will have normally given a favorable opinion in the first place. If, however, the idea is that the member is looking to fight the case on appeal, very often the PEB and/or the approving authority will not respond in a meaningful way, which will give a basis for appeal. However, many times, you can accomplish the same through other means.
It is hard to think that, in the absence of a profile or evidence that your condition has impacted your duty performance, an outside opinion would have much success at the PEB. The corollary is that if you can get evidence of significant duty limitation, the profile and the supportive Narrative Summary will likely follow (and obviating the need for the outside opinion). The point is, the former will be required in almost all cases to get a fit finding anyway. Developing that kind of evidence is what I normally advocate.
TDRL members have some different considerations as they are usually seen by a civilian after they are retired. Also, as I posted elsewhere earlier today, the analysis is completely different at the VA (though many of the same considerations as to weight of opinion are still operative). As in every case, you must look at the actual circumstances of the case when deciding how to proceed.