I would concur that EP cells are a good reliable cell - the new 4600 cells are out and hitting the shelves.
LiPo is good but may not be legal where you race. They are lighter and will alst mor cycles than NiMh cells but certainly not forever. I raced 6000 Mah MaxAmps LiPos for about 8 months once or twice a week (I had 2 packs) before they fizzled out and went flat. They both went flat about the same time. So, they last about 2 times as long as NiMh (give or take) and don't generate the heat either. You MUST have a LiPo charger and youy uSHOULD have a LiPo cut-off speed control. Running below 3 volts per cell or charging higher than 4.2 volts per cell is a good way to kill your cells. LiPos should be balanced every time they are charged - you can get by with checkign them every so often if they stay in balance but if they don't stay in balancec then you MUST balance every time they are charged.