you ask the most ambiguous questions most of the time.. you have to experience it yourself, or at least furnish more details on what type of shots you use the most and what are your strength/weak shots before anyone can reply to you...
the NS9900 is stiffer than the arc 11, and has a very quick repulsion, its easy to return shuttles with good clearance. the arc 11 is cushy, but it doesnt mean it cannot do the same, the way you swing/stroke matters..
The power for smash ok?which wabt u think ok for smasher?