Sagey and Tim C...
There's obviously been a lot of good advice and info in this thread. What you have seen is a wide cross section of the FAA all giving you their perspective and selling the merits of each aviation job. (I'm an observer but my two points are not role specific:
Firstly, the AIB/selection tests probably have changed since many of us did them all those dog watches ago! But, a couple of things will be the same; A broad view of military/current affairs is essential and
irrespective of the type of leadership test, the selectors will be looking for common sense and stacks of enthusiasm.
Finally,(sorry if this repeats any comments in the thread) the advice given by those of us currently serving is obviously a present day viewpoint. Your career will hopefully span one of the most exciting development periods that the RN and FAA will have experienced in our generation. New Carriers, Future Combat Aircraft replacing the Sea Harrier, AEW Mk7 coming on-line and progressing down the Future Organic AEW route, continuing introduction of the Merlin and Lynx replacement(?). All of this kit will be cutting edge for once and not put together on the back of 20 Benson and Hedges.
What I'm saying is, don't just focus on what we have now, but look at what fixed/rotary/pilots/observers will be doing over the next 15 years or so and where you'd like to fit in (this will also demonstrate forward thinking on your part during AIB interviews).
Good luck in whichever specialisation you choose...see you in the bar!