I don't know if shadowpriests should be that far below fury warriors. We're no more hybrids than they are after all. 10% seems a little harsh.
I do see shadowpriest as a bit of a frostmage though, paying for high survivability with slightly lower dps. I don't mean high survivability when an untanked raid mob comes stomping you into the ground, but shadowpriests do very well against aoe damage. You passively heal yourself for 1000 hps, you can dispel, you hit the shield whenever you take damage if you aren't certain that no more will follow, and you have Dispersion for big predictable spikes.
Shadowpriests are in fantastic shape for pve. I hope it stays that way.