I still think combat = win, however I found that burst mutilate was useful for solo grinding. you take very little damage and tear mobs apart rather quickly. I also found it easier to get good DPS daggers rather than swords for most of that range.
http://www.wowhead.com/?talent=fMecoxTsVzVoZV0eMMh I personally like variations off of this build. Its good for XP levelling for the burst damage, and its good for pvp with some of the traits.
the idea is to open with CS in PVE, then as soon as a poison ticks (or before CS is about to run out), pop a mutilate. wait till your at ~70 or more energy, kidney shot, and double mutilate. if its not dead you have 5 CP to finish it off in, and the mob is stunned at least half the fight.
its not the best instance damage though. thats part of what improved ambush helps with. improved ambush is also great for battlegrounds as well.
you can go down the combat tree if you want. as you start getting DW spec that will outdamage opportunity any time.
combat is still best for instances, but this spec is an interesting change up if your getting bored.