No, the backphone on the DEUS headphones is not compatible with the clip systems on either the earlier or latest WS1 models. On DEUS, the clip system for the earphone is different. It is very easy to unclip the earphone in order to replace just the backphone in case of wear. Remember that what we refer to as the backphone includes the flexible headband, the loudspeaker and the foam. It does not include the electronic unit which can be unclipped (the left earphone). The DEUS backphone is as flexible as the one on the latest blue WS1, and is black for purely aesthetic reasons!
No, because the digital link protocol and the frequency band are both different.
DEUS operates on the 2.4 GHz frequency band whereas the WS1 works on 433 MHz.
In fact the essential difference is that the DEUS headphones are not just wireless headphones like the WS1 and WS3, they are also the detector's brain when the remote control is switched off or absent. They enable most functions to be controlled via their LCD screen and keypad.
To turn the headphones on, press only the [-] button. To turn them off, press both the [-] and [+] buttons simultaneously.