Many thanks Stimmer to have 3rd party independent tested the serial USB issue on DUE's programming port and validated it works as i've claimed on UNU, MEGA 1280 and MEGA 2560 (all rev).
As I've mentioned before, this SerPro has been used on critical software and power electronics for open source alternative scientific projects in many countries for more than 2 years wether Mac, PC or Linux.
Let's hope the arduino team resolves the issue.