simple answer is no you don't need a heated bed. ABS is the only one that benefits from a heated bed. A heated chamber assists really well with Most prints and stops a lot of "mysterious" problems. The issue relating to Banding etc from the bed heating is more related to power supply issues than anything else. Make sure you use heat sink compound on your Tip thread, thermistor, Heating element and any other areas that rely on accurate thermal readings. (makes a big difference) Also you should be running a PID setup at the temperature you print at for each type of plastic you print. I use PLA, PLA+3D, PETG, PETG+3D and ABS and have a PID setting for each one, and none of these that I print uses a heated bed. The bed is covered with Blue painters tape, then rubbed with isopropal alcohol. On thin sections and ABS I use an enclosure with Hairspray on the blue tape. In my designs you will find a Repetior Host startup gcode that shows how this could be done(PID).