I agree, loose loops are neither a perfect nor particularly effective workaround to this issue. Although somewhat tolerable, it's extremely unpleasant to use, not to mention incredibly limiting, especially when attempting to communicate with a Processing sketch (or anything else using serial). I hope that someone can share a better solution soon. It's been a long time, and the Arduino Uno is effectively br0ken on GNU/Linux. I'm sick of unplugging, replugging, slow IDE UI, removing lock files, and jamming the reset button and upload code buttons repeatedly.
Does anyone know how the efforts to "fix the linux kernel CDC ACM driver" are going? Are there any efforts to validate the behavior of the 8u2 implementation of a CDC_ACM serial device?