Consider changing inheritance scheme

[JM-FRANCE]

Why do you need to inherit from SoftwareSerial rather than Print? (cf http://playground.arduino.cc/Code/Printclass )

That would allow to implement a simple scheme where you would pass at initialization a pointer to either a SoftwareSerial or HardwareSerial object that would become your print target in your code and leave the choice of hardware or software serial up to the user of the library