So....no proc for shock? No thrash? Yeah....good luck. I run 10-13 specs for my assassin, I'd never use a thrashless darkness. Seems like a waste of time honestly.
It's true, I only proc off of Assasinates. But what use is an auto-crit shock when your out of force? And if you only thrash once in a while (rather than twice every cycle which is nearly force-exaustive in 31/0/10) then you only get the proc once in a great while... not a huge sacrifice.