I guess I did the exact opposite of your advice, but not intentionally. DD FS300 28/17 was pretty much toast, so I grabbed at 29/17 I had sitting in the garage and let her use it for her hitting lesson. She did pretty well. Her hitting instructor said she handled the bat well. Although I did go up in length one inch and dropped her to a minus -12 vs the -11, I anticipate that it will be a short stop. I really didn't have a choice because I didn't want to buy another 28/17 bat. The good news is Easton has another one on the way. It should be here tomorrow. I have to give them credit on the speedy warranty service.First, realize four things. #1 The Vendetta is a middle of the road composite bat performance-wise. #2 You will probably be buying a new bat about every year and sometimes sooner as she hits her growth spurts. #3 You want her swinging the longest heaviest bat she can as long as her swing mechanics don't break down and she maintains her bat speed. #4 You want to try and get her into a -10 bat as soon as possible. This means that if you have to keep the same length and go up an ounce in weight, do it as long as point #3 is followed. The more mass behind the contact point of the swing/ball, the further it goes given the same swing speed and mechanics. At this point, if your DD likes the feel of the Demarini bats, stay with those. Otherwise, move on.
I think she has been in a growth spurt since the day she was born. We usually have to buy two pairs of cleats per a season.