I would try to give some main points on above review. N50 II are head heavy, and more flexible than F9, as a result it is slower but more powerful. On the other hand, F9 is stiffer and cuts the air faster due to its frame profile which is less air resistance similar to kason TSF 300A while N50II has box frame profile similar to Ti.10. According to the reviewer, N50II has more stable frame compared to F9. Hitting sound from F9 is clearer and producing crispier sound than N50II. When hitting shuttle, N50II has softer feeling than F9, however F9 vibrate more upon hitting. Additionally, F9 has better control than N50II, while N50II is more repulsive. F9 is better in netting too. BP : N50II 293mm, F9 287mm N50II suitable for Singles while F9 for doubles.