One thing that has to be considered is the size of the head you are attaching the shaft to. The bigger the head, the les torque you want. If the head is over 360cc, then you need a shaft rated at 4.0 (or close) or less torque.

My advice is that if you like the NV, stick with it. It is a good shaft for the larger headed drivers. If you are looking for some other shafts that work well with oversized drivers, check out Harrison's Titanium line.