You could do well with either Annihilation or Carnage while solo leveling. Annihilation offers more self heals and theoretically higher damage. I've found, however, that my damage output while solo leveling is actually much higher in Carnage, just because of the fact that things often die before my bleeds take their full effect. Once I realized that I switched to Carnage and I am able to burst down weaker enemies much more quickly.

Here's what I don't like about PvP specific stats. First, there is no strategy or decision making involved in choosing the stat; everyone wants it. Whereas other stats involve some decision making about what kind of build you want, like choosing between crit chance or accuracy. Second, all it serves is to create a barrier for entry to new players. You don't have expertise on every single piece of gear? Oh well, I guess you're going to spend hours getting killed and losing until you have it. This is the opposite of fun. I didn't like it when they added resilience in WoW, and I don't like expertise in TOR.

I think the reason most people don't take the talent is because in a group PvE scenario, you should never be the one getting hit. If you are, cloak of pain is just an "Oh Crap" button. All the talent would add here is increase your damage output even more, which you don't want to do anyway if you pulled aggro from your tank. In a PvP scenario, there are just better talents out there, like the immobilize on deadly throw. Where this talent really shines though is solo leveling. I'm using it right now, although I plan to switch away from it when I'm done leveling.

I second the vote for a force pull. In fact, I think it should be a base ability for warriors. Juggernauts could use it to be a better tank by pulling attackers off their squishies, and Marauders could use it to help with being kited.

That sounds like a challenge.

Back on the original topic, I wonder if the observed difference in damage on force scream might be related to different resistance levels in pve. Maybe it's the case that enemies in pve tend to have a lot more energy resist than kinetic resist, so that gore helps force scream less than it helps lightsaber attacks.

I love this idea, and there is already a push mechanic in the game, so it wouldn't be hard to implement. I agree with other posters in that a pull would be more helpful than a push for a melee class, but either one would be a lot of fun to have.