Because of the uncertainty, I have temporarily removed S5 from the list of supported devices, but if it does work I would put it back quickly.
I posted the app here for download. Could you test it for on your device? Send me a PM, and I will get you the APK. Thanks for your help!
BTW This is S for Switch Voice:
Whenever (and however) you launch S Voice , S for Switch Voice will switch to Google Voice Search instead:
►Voice wake up (Say "Hi Galaxy" with screen off)
►Double tap on the Home key (turn on "Home key" button and adjust monitoring sensitivity)