If you're still on the lookouot for some Labor Day Sale, checkout Black Ops Airsoft Guns and today's the last day of their sale. When buying airsoft guns, you get 10% off, for everything else they have available, 15% off and free shipping for orders over US$125 (better check if this is continental U.S. only). No coupon codes to put in as the discounts are already applied upfront.

Also, they have made a video comparing the rates of fire between different types of LiPo and NiMH batteries which should pretty much help you understand the differences among these batteries.