I agree wholeheartedly with Victor. While an armor save is an excellent idea for griffins, there is absolutely no reason to add a complicated and unneeded armor option. Simply give a griffin a 4+ armor save and call it a day. It'll be a great excuse for GW to produce an awesome armored plastic griffin model with both human and elven riders.
This is something I've been thinking for a couple of years now.
That plus a points reduction. But, let's face it, even the points reduction would be sufficient. 150 and I'd start using him again. Like, seriously. The model's awesome, so it's a damn shame you can't really use it.
Or as I always say, you can use anything - just deploy - but killing your inner child in the process just because your behind hurts so much after the game just isn't right.
And look at the Dark elven Manticore... Just look at him and tell me the current rules for a Griffon are justified...