I'd think disengage in combination with the goblin's racial rocket jump ability would be pretty OP in PvP. Not so much for BGs like WG and AV, but more for the 2v2 or 5v5 arenas. This is purely an opinion, for none of us know how Cataclysm is going to work untill it's actually released.
I got the idea the goblin racial jump was going to be a targeting circle based thing, 2 to 3 minute cooldown, and as a consequence very clunky in split second scenarios. Besides that, it's hard to tell where hunters are in PVP w/o Aspect of the Fox, since at the moment we're really burst reliant... while we rapidly die to almost any combination of dots imaginable.
And once we do get Aspect of the Fox... we will be able to properly strafe kite people without really using disengage, so I'm not sure I see the benefit in this combination?
The 2-3 minute CD is why I would think it'd be better for team arenas because of the wait time in between. If you're good with your mouse, I don't think using it in a split second scenario would be very difficult; but I do see where you're coming from. I think I can safely say that, at the disposal of a skilled hunter (even with fox), I can see this being an effective PvP combination in team arena. It wouldn't put Goblin Hunters leaps and bounds ahead of other hunters, but would it be a small advantage? I would have to say yes. I appreciate anyone's opinion on this, for I believe it is worth discussing