Where do you stand on the visual design of the hippogriff? For me it depends on their origin, as the mythological griffin is described as equal parts lion and eagle, with the hippogriff being the rare offspring of a horse and griffin, because, as in Dungeons & Dragons, griffins really like to eat horses (which sucked because they were easier to deal with than griffins).
Dungeons & Dragons, on the other hand, divides them into two similar-but-separate critters. I say, why not stick with a theme? Lions and eagles are griffons, horses and eagles are hippogriffs, and I am totally cool with them having a horse's arse with a full-on eagle's head (I think that the 3rd Edition hippogriff looked kind of odd with the beaked-mouthed horse, though the hoofish-talons were kind of neat).
I think the image above is perfectly serviceable (though it was odd that it was the only hippogriff I could find in all of Magic: The Gathering). Similarly, the hippogryph from World of WarCraft is another solid example, albeit with antlers. Actually, why not go further and mash other things with eagles? It is not like animal-plus-animal monsters are exactly an innovation in the game, after all.
You could even try to tie the entire griffo-sphere together with a similar origin, whether it is crazy wizard, nature spirit, or eagle god. Maybe a couple of wizards/spirits/god decided to have a bet on who could make the best eagle-combo.