I belong to a FB group that has a gentleman who tests new model bats and reviews them. He has 2 hitters swing the proper size bat from the age groups of 14U, 16U, 18U and a couple of D1 girls while he takes exit speed readings and averages them across 10 balls. Basically, the review of the Carbon went something along the lines of the D1 hitters asking if the bat was even legal. Average exit speeds surpassed them all by 6 MPH with the fastest exceeding the fastest exit speeds of any of the others by 8 MPH. As for the others, according to his numbers, forget about the Axe. The Mizuno PC, GA, Meta and Mantra exit speeds are all on par with each other (within 1 MPH). One thing I've found is that each hitter is different. They like different things about different manufacturer's top models, have more confidence in them and depending on the variations in their swing mechanics, will be able to take advantage of one model over all the others; even within the same manufacturer's model.
For example, I took a road trip to SPC with five of my players that were looking for new bats. After trying all of the top contenders mentioned, 1 player ended with a tie in top exit speeds between the Anderson Carbon and Marucci Echo 2 piece. She liked the Echo a tad better because of feel and took that one home. Another player had the highest exit speeds with a tie between the Ghost double barrel and the Mantra. She went home with the Mantra because of both her liking the feel better and concerns over longevity issues. Another had hands down, the highest exit speeds with the one piece Echo, even over the two piece Echo. The fourth player had her highest exit speeds with the Meta. The next closest was the GA. It was 3 MPH slower. Last but not least, the final player ended up with the Carbon because it exceeded the all other models by an extra 5 MPH of exit speed and she liked the garish green paint job.
The exit speeds off of the bats not selected by the various players mentioned were all within 1 MPH of each other. The bats selected were on average of 2-4 MPH faster than the others in exit speeds.
The moral of the story? Every hitter is different and the best bat for one hitter isn't necessarily the best bat for the next one.
We finally made it to SPC last night, and they did not disappoint. My dd thoroughly tested the Meta, new LXT, Marucci Echo, Anderson Carbon, Demarini CF. She also worked in her existing bats (drop 9 22' ghost, 20' mizuno pc, 20' demarini CF ext) for feel and performance comparisons. She had already excluded Mantra having already tried it. The only regret was not having the GA in her size to try. So I won't rule out another bat in the future when she finds one. My dd does not want new shiny toys just because they are the new hotness. So I trust her enough to say we will get any bat if you fall in love with it. Of course Meta is all the rage, and it's an awesome looking bat. So I wouldn't have faulted her for choosing it. But..
By feel in her hands
1. Echo
1b. Meta
2. CF
3. LXT
4. CF ext
5. PC
Favorite to swing (whip and control)
1. CF
2. CF Ext
3. Echo
4. Meta
5. LXT
6. PC
7. Anderson
Max Exit velocities (from a tee)
1. Tie with her ghost and CF (3 MPH faster than the rest which I also found odd since one is a heavier end loaded and the other extremely balanced and lighter)
2. Meta (+1)
3. Echo/LXT
4. Anderson (-1)
(Did not try the PC, CF ext)
Consistency of hard hit balls (from my eyes, and EVs)
1. CF
2. Echo/Meta
3. 22' Ghost
4 Anderson
6. LXT (this one baffled me. I can't figure why she wasn't feeling the LXT)
* I will not pretend that I know what I'm doing. I'm sure there are factors you more experienced parents/coaches would have paid attention to. But based on a lot of advice on here, I just wanted her to evaluate everything for herself. I was not intending on buying yesterday. But she legit fell in love with two in particular. The CF and the Echo. They were neck and neck, and she already has the CF ext which seems to be almost identical in performance and feel. Plus she felt a whip from that bat she hasn't quite felt before. So that was the winner. I honestly think that if they weren't clocking the EVs though, she walks out of there with the Echo. She kept coming back to it. So at the end of the day, I don't know if I really learned anything scientific. But I do know my dd is excited to use her new bat, so that's nice.