12-servo power source selection

Hi,

I am new to servo-based projects. I recently assembled a lynxmotion 209 with 12 servos powered by a standard 6v. 5-NiMh-battery pack(rechargeable). Should I change the power source to a 7.4v. Lithium polymer battery ? The reason for me to raise this question comes from my observation of short lifetime[1.5~2hours at most] of my current power source. By lifetime I mean the length of time my lynxmotion 209 device can run on that fully charged NiMh battery pack. If I change my NiHm to a 7.4v LiPo, would it extend my battery lifetime ? If so, Do I need a voltage regulator for my servos and how to connect it to a Lipo and a SSC-32u servo controller? How should I connect a LiPo to my SSC-32u servo controller ? Do I need a power connector converter?

My appreciation in advance.

Here are some threads discussing powering servos.

Thank you so very much