I'm pretty sure the clutch twists in the same direction so you would be rolling off of one while rolling on the other. Seems pretty intuituve to me.How about the retraining that would be required to operate a twist-clutch? I've never tried one, but it would seem a bit awkward, as you are simultaneously twisting the throttle with one hand and the clutch with the other. I would imagine your brain might have a hard time separating and synchronizing those to movements.
Of course, I've never ridden one before so I could be completely wrong.