PG35L Micro Extruder for Printrbot Simple Metal (E3D v6 and Ubis hotends)

I ran into a lot of stepper skipping with Printrbot's aluminum direct drive extruder (stock on the Simple Metal), even with active cooling on the stepper motor and the current pots adjusted (up, down, middle, anywhere). My Ultibots K250VS kit introduced me to the world of skip-free extruding with their PG35L-based micro extruder, so I modified their design to fit the Simple Metal's bracket and ubis hot end. Later I realized that the uncooled ubis hot ends are total garbage (I can't speak for t