FYI QPST Works Fine on M8
This is just an FYI
Just loaded 56018.PRL using QPST 2.7 Build 402 on Windows 8.1 x64
Smooth as silk.
It's really not a bad idea to make a backup with QPST as well. It saves settings in the phone that TWRP / CWM do not touch.
Couple folks have partially bricked phones in the RECOVERY thread.
Samsung Galaxy S5 with R.O.D.T