What would make the idea even more interesting is if, like pallies at 20, griffons could be a summoned mount, also. I would pay about 100pp to have my very own griffon. That would be so unbelievably cool! And, if you purchased one, you could ride him into battle and you would get an added combart art skill that said "Claws of Ravaging" as a bonus and you could chain together an HO with him.
/sigh
If only...