Tiger,
AFPS05 is not terribly complicated, but is widely misunderstood - especially by those not on it.
As an example, but I don't want to have to go through all the fine detail, if you leave the RAF on AFPS05 at 54 years 364 days you (ultimately) get more money than someone who left at 55. You just don't get it as early (hence your personal circumstances are very important).
Exactly how far before your 55 point you can leave under AFPS05 and still get the same amount of money as if you had stayed to the end I haven't calculated, but it wouldn't be too hard to work out!