I thought about this the other day as I was doing it. Badminton gyms usually has a very high ceiling. So you hit the shuttlecock as high as you can using forehand and backhand a few times and see which racket you can hit the highest with. Then that's the racket you should use. It can be applied to choosing string tension or string brand as well. Of course, not everyone has the means to test many rackets this way. I'm just wondering if this concept is a valid idea physics-wise.