When I test on the ptr I notice about a 500 dps increase if i jiggle when I have to reapply my plague, and when I use swd. If I take the time to plan it out and I have 2 GCDs in a row from reapplying plague and swd back to back, it goes up a bit from there even.
So yes. Jiggling is a very good thing to do for any spriest in the expac. Even if you use your mouse to click those two buttons while you use your strafe keys to move back and forth, or use keybinds and your middle mouse button(if you didn't rebind it) to move forward while you use them two buttons.