I have GMed a fair share of games actually, but most of them with a group of friends in reality. I've ran some on forums before, but mostly Solo games. I have tried my hand with some forum games with groups, and it seems to be possible, and fun, with the right group. Disappearances that eat people are not so fun but happen, sadly enough.
Now, as for the race. I like what you have going on there with the Horo, but as pointed out by PhantomPistoleer I prefer to keep this to a limited set of materials if possible to avoid being overwhelmed by it.
I'd appreciate it if you were willing to play a more standard race found in the booklist that was OK'd with the group of players before. I got nothing personal against exotic races, but one of the ideas was to limit down some books and such so that players are on the same start-line, not having to complain about unfair advantage I'd granted someone.
I think it might be possible to have a character who is stat-wise, human, elven, whatever race you pick, but during the Druid Training got messed up with transformations, resulting in a -partial- return to human/elf/well, base race form and partial traits remaining, like the exotic ears or tail.
No in game penalties or bonuses, even if the senses were sharper they would be so 'new' still that the character wouldn't be able to make any special use of them still. Flavor addition with a good story reasoning? That I think I can live with (and it doesn't give unfair advantages to anyone) but I figure that its not exactly what you got in mind, still.
Anyhow, just tossed it up for a thought anyway.