I just get Nano9990 and play with it last night.
It is very easy to play with and slightly similar to tantrum200 in term of swing speed.
It is slightly head heavy, mid-weight, moderate stiffness, very repulsive with birdie contact, the smashing is very precise but not "boom boom" kind of smash. It is definitely good for double game but it can be used for single as well.
So far I have played with AMP90, Lethat60, Furious608, VH1500, VH1700, Tantrum200, Tantrum130, Nano900(P/S), ES10,ES9,ES7 and Nano9990. I would say the Nano9990 is very much on par with the Tantrum series.
Power: 8.5/10
Control: 9.0/10 (Very accurate in term of placement)
Stiffness: Moderate
BP: Slightly Head heavy (before put on the over-grip)
Tension: 25 x 27 with BG65
Hope it help .....Cheers






BTW, can someone review the Z-Spark