It's true, I only proc off of Assasinates. But what use is an auto-crit shock when your out of force?
I like to use the PVE gear set bonus granting +50 power. Works wonders IMHO. You can still have 1200+ expertise. Or you can grind off-hand to fill the shells and have max expertise.
I use it for deception so I have 160 force in total. You could still have 150 though.