Remember that an NDB is a non-precision navaid and the minima that are used are appropriate to that. But the clue is "non-precision", ie. It is not very accurate. So, by comparision with a dead accurate, fully updated GPS it's performance might appear to be woeful, but it does do what it says in the tin. Unfortunately, Mr Bush has a veto on your GPS approach so I'll stay in the stoneage untill that changes.
PM.