The bootloader is preburned in factory from Atmel and is stored in a dedicated ROM memory
quindi non sarà possibile aggiornare il bootloader? 
It is possible to erase the Flash memory of the SAM3X with the onboard erase button. This will remove the currently loaded sketch from the MCU. To erase, press and hold the Erase button for a few seconds while the board is powered.
questo invece è ottimo 
The Programming port is connected to an ATmega16U2
hanno lasciato il 16U2 mmm
The Native USB port can also act as a USB host for connected peripherals such as mice, keyboards, and smartphones
Buono molto utile,sopratutto la separazione dall'usb di programmazione.
Uploading sketches to the SAM3X is different than the AVR microcontrollers found in other Arduino boards because the flash memory needs to be erased before being re-programmed. Upload to the chip is managed by ROM on the SAM3X, which is run only when the chip's flash memory is empty.
Interessante anche questo,
@Massimo facevo solo delle considerazioni non facevo critiche o complimenti 
Era ovvio che non era possibile aggiornarlo in quanto la dicitura ROM sta a significare Read only memory,
semplicemente non mi sembrava pratica come questione in quanto risulta praticametne impossibile aggiornarlo,
e sappiamo tutti benissimo che i bootloader covano moolti bug 