absolutely! the longer the barrel, the higher the bat speed at the end of the bat and also at the sweet spot, since the end of a bat covers more distance than the knob during the same swing. this i the same reason why pitcher who are taller (and thus who have longer arms) throw with more speed than shorter ones.
The disadvantage of going with a longer, lighter bat is that it has less density so the ball won't go as far when hit. I had both my dd's swinging -12's until recently when my dd's hitting coach recommended my older dd go to a 32/22. I thought he was nuts at first because she never swung anything longer than 30" and heavier than 19 oz but sure enough she's hitting better than ever now. I'm looking for a good 30/20 for my younger dd now.
I have a 30/20 louisville slugger tritan composite with probably only 25 hits on it. Great bat but my daughter ended up stepping up to a heavier rocketech. If your interested shoot me an email and we could talk price. Thanks firstname.lastname@example.org
Thanks for the offer but I just found what I believe to be a great deal on the bat I wanted to get her, $115 for a 30/20 scn1b (price included shipping). I'm expecting it in a couple of days and can't wait to get dd some bp with it.