To the Wazz/Footman conversation of Gryphons & Tanks... I naturally have to stand up for/defend Footman a bit here, as I went through something similar in designing my custom Jungle Troll race. The challenge in making an entire "Faction" (comparable to the original 4) out of a singular "Race" is that you lose a lot of the diversity available to other Factions (i.e. Alliance is Humans, B.Elves & Dwarves... Horde is Orcs, Trolls and Tauren... But Dwarves are just Dwarves. Trolls are just Trolls (lol)). This can make coming up with mechanical, flying, and even some basic combat units, challenging.
I faced this discussion with another individual I respect, challenging my decision to include 2 "Bat" units in the Trolls. For a variety of reasons (not the least of which is how few "flying units" make sense for J.Trolls), I included 2 "Bat" units; one a "Vampire Bat" (light anti-air flying unit with melee bite attack; excellent scout & deals better damage in groups) and a "Bom-bat-ier" (medium/heavy flying mounted unit, ranged Siege attack or whatevs). I tried to make sure they were as different as possible (in terms of both aesthetics and gameplay), and I feel it's a good combination. However, it still can look unimaginative to those just glancing over it. So I feel for you, Footman16.
However, I can understand a bit of what Wazz is saying; you have two nearly identical units (at least in terms of aesthetics; both are dwarven-mounted gryphons). ((I won't go into whether or not the particular models go well together; SoC has great resources but a tad un-Warcrafty IMO)). Granted, they perform different Gameplay Roles, but that's not intuitively obvious from looking at them (an incredibly important element of game design (i.e. Team Fortress 2)).
Similarly with the Tanks. I LOVE that model... But it's just like an uber (or even Heroic) version of the original. Next to the original, they just kinda look... sad. :<
Now, as a caveat to all this, I haven't downloaded or tested anything. Perhaps the tanks/gryphons are really quite different in game. But even if they are (& especially if they aren't), you may want to consider some options for greater differentiation (esp in terms of aesthetics).
Good luck! Making races is hard. I'll make sure to try to do yours justice when I finish
my Dwarves.