i tried using a QWERTZ machine once- I do touch type, and had read somebody who said he could switch back and forth with QWERTY after making a few errors each switch. I found I could do it if I thought about it, of course, and as soon as I thought about writing rather than typing I would begin typing sentences like... she was verz tired after a long daz. 

I was afraid if I worked at QWERTZ any longer I would foul up my touch typing and never be a able to keep those letters straight again, so I stopped. Now, maybe AZERTY would be so completely different it would be easier to keep the skills separate: like reading music in bass clef and treble clef, though AZERTY seems as oddball to me as alto clef.