Caveat: I am not a WoW player.
From doing a bit of Google research, it seems that yes, you could certainly use the half-dead to simulate forsaken. They do not have the "cannibalize" ability (racial feat, perhaps?) and they seem to be a bit more alive than the forsaken (at least from what I was able to read), but that might be a matter of flavor at the table. I'd say go for it.
@OBE: It's immediate reaction, not response, since you are using the GSL (for the two feat powers)
Like I said, not being a WoW player, I saw an undead-like race, with some of the same abilities (and I think that Cannibalize ability from the forsaken could totally be a racial feat) that could more or less fit in. As a player of the game, you'd have a much better understanding of the race as it plays, but as far as window shopping, I think it could work out.Not getting the Forsaken-vibe at all, and I had 250+ days played in WoW when I quit.

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.