I never hold full up elevator on take off roll. Yes I taxi with elevator up. Then I set up and let the plane roll. Usually the elevator is at neutral, I do however tend to think what the ground/runway is like. For some or other reason if I know we are using the grassfield runway, I know it's not smooth as the gravel and the grass makes it a bit more "sticky" for the wheels. In this instance I tend to give a little bit of up elevator - it seems as if the plane then gives a much smoother take off roll and gets in the air faster. On the gravel runway it isn't neccesarry.

So it depends on surface for me. Stupid probably, but it hasn't had a bad effect as if yet.