I've had an UM2 for 3 months. It works well with both 1.75mm and 3mm filament, ABS and PLA. With the 1.75mm you need to go into the settings and create a custom profile, but it feeds adequately. We buy our filament from the cheapest vendor we can find on ebay. Our only problem was with some PLA that had been opened more than a month ago; it became stiff. We built a reel holder that feeds directly from the back, with fewer turns. That works well even with stiff PLA. With ABS, the only way I've found to get parts to consistently anchor to the baseplate is to paint a slurry of acetone and dissolved ABS onto the baseplate before printing. We run 40-hour print jobs all the time, and have never had trouble.