JB-King is "1:1 copy" of TB so it is on Actel and well protected as TB. JB2USB is on different chip (there was suspicion it is on Atmel but probably wrong). Different chip means that jb2usb developers reversed TB firmware (converted into source code and recompiled to own use). In GraVoX theory this dongle is less protected.
Due to this it is better to concentrate on jb2usb and that is what GraVoX and Mark Webber are doing...