Just printed another benchy with 2mm retraction @ 70mm/s. Also tightned the spring force on the extruder. Came out the same or slightly worse. Seems like the new extruder setup just doesn't work right. I assembled it carefully according to the instructions, gear turns smoothly, no backlash, etc. I'm stumped. About to leave town for 1.5-2 weeks though so I guess I will have to try when I get back. =P