I think Impulse Drive spam was superiour at some point but not any longer.

True Thrust + Vorpal Thrust would be a combined 390 potency (150+240)

Two Impulse Drives would be 380 combined potency (190 x 2). So ten less potency over the same length of 2 GCDs. I don't know the intricacies of damage calculation but that seems like it makes it superior, even if barely worth the extra effort. But it's a lose/lose situation. Either the strategy for the class is even more brain dead than initially thought since you can do something easier and get more performance, or it has a useless skill for 32 levels (Disembowel is at level 38).

You get Vorpal Thrust at level 4, and Impulse Drive at level 6. So there's never a point where you can use Impulse Drive but can't use Vorpal Thrust.