I cannot believe that "converting from a piper to a cessna" is even a topic for discussion.
bye the bye on my licence test flight the examiner required me to do a takeoff in the cessna with full flap.
I argued with him for half a runway but eventually he persuaded me.
all that happens is that you need to push a lot of nose down elevator to counter the centre of pressure movement.
you can actually takeoff with 40 degrees of flap.