Dem double ended ones won't work on an impact (my main screw gun) unless you locate a real deep bit holder that will accept it. I have yet to see one.
Also have never had any luck keeping a flat head bit on the screw without a sleeve to keep it in place on the screw. Most of those type won't hold up to the abusive torque of an impact driver. (I have killed many aluminum ones, and stick strictly to steel ones now.) Infact it is hard to find bits that are not too brittle to use with an impact driver lately. Too soft a metal - they cam out too easy. Too brittle and they shatter. It's hard to find the right balance... I'm the type of guy that has few torque settings if a few 'tacka-tacka's' from the impact are too much... I twist it by hand.
"Well - I oughta....." -Jackie Gleason