MarkM:
Stick a 400 point character (with magic items, marks, equipment and gifts) on top and it would still struggle, unless designed to be immune to fire (which, honestly, people don't take very often on things that don't care about fire one way or the other).In my gaming environment (roughly 1 tournament a month in the UK) one or both of the 2+ save items are taken in almost every army.
Hashut's Blessing
Whether the model suffers (to flaming) is irrelevant. There is so much flaming stuff out there, having a model which is almost immune to it is very useful.
Your point about opponents not having the book is totally valid. It's why I have a single sheet crib sheet with all the 'odd' stuff on it, plus the Lore of Hashut, which I give to my opponents prior to the game.
In addition I give them my army list (excluding magic items) so that they can see all my unit stats.