I've had a v6 (1.75mm bowden) for a couple months now, and I really like the kapton-less design, the ability to switch out nozzles, and the overall reliability of the head. As predicted, my PLA mount has been more than adequate, since the heat sink remains cool as long as the fan runs. I've produced some very nice prints, but I've also produced some really bad prints. First layer, and reliable extrusion speed have been my hobgoblins. If I lower the speed dramatically (25mm/sec for first layer, 50mm/sec for the rest), I can get quality output, but anything over that starts getting questionable. 60mm/sec seems to be absolute fastest I can lay down filament. I've tried both the 0.4mm nozzle and the 0.6mm (Where's the 0.5mm? ), and I've made improvements to the extruder (better hobbed gear, drop micro-stepping to 8), and it's helped, but some filaments just Don't Like Printing. This weekend for comparison's sake, I installed my original J-Head (0.5mm), and it was immediately obvious that at the same temperatures as the E3d, the filament extrudes with far less force (half as much?) through the J-Head than it does through the E3D. Is this normal, or am I doing something wrong?