I can tell you from personal experience that when it comes to sounds and vibration analysis, those folks at the NTSB have really got it wired. Voice analysis from the CVR however, can unfortunately raise more questions than it answers, especially if it is an analog system (wind noise really messes things up there).
I suspect that the other systems were ruled out via the black box system analysis, hence the big mystery as to what brought it down, and that is of course assuming that all operating systems have a feed into the FDR. There are some big dam birds down that way, and hitting anything center mass on your window that weighs a couple pounds at 140 kts is always going to be dramatic. I am curious to see about the strengths of these modified wind screens, and if they can be shown to be a causal factor.
I would also like to know if the pilots were wearing helmets, with visors down? Are they even required to wear helmets?
Best of luck to the investigators.