I ended up with 3 IoB griffin models after some trades, so that's what I'm planning to use. They're on ebay for about £6 each, and since the Imperial Griffin is now the same size as Altdorf, their slinkiness is just right for MC.
Not sure how much effort is required with the front claws - you could leave them on flying bases (like they're leaping through the air), or just re-pose one/both claws to point down.
Not much help if you hate the idea of Demigriffs - but an obvious solution if you're on a budget and don't want to fork out £10 per critter.
On a side note:
Any ogre players tried out alternative models for mournfang/rhinox/thundertusk/stonehorns? I've looked at Schleich and Papo bulls/bears/rhinos, but not sure of the scale. It's getting harder to pretend I'm wargaming and not just playing with toys