Same here. Because I can whack a ball pretty good, most of the girls on my team want me to put "daddy swings" on their new bats to help break them in. I get to use all of them when I do this, and I've found that the bats that flex a lot don't work as well for me as ones with stiff handles. So, I normally hit the ball a bit farther with one-piece designs and it is even more pronounced when I swing a very flexible bat like a DeMarini CF6.I have been know to hit a ball pretty well once in a while, I prefer one piece over 2 piece. Two peice bats flex too much for me. I have also seen plenty of smaller guys with major bat speed prefer 2 piece.
Thats why I never say one bat is "always" good for one type and another is "always" good for another type hitter. Depends on the hitter and also on what they are more comfortable with.
It doesn't mean the DeMarini is somehow inferior, though. Quite the contrary! Sometimes the flexibility really helps deliver more pop for certain 11-year-old girls. Conversely, a stronger 11-year-old girl might generate more pop from a more rigid, one-piece (or 3-piece) design. You just have to use what feels best to the girl and what passes the eye test for you.